Radiotrope B+ low

6/2/2003 11:20:07 AMsean

Hello, I tested 71a tube voltages. from pin 1 to pin 2 is 75 volts. from pin 1 to pin 3 is -13.95v.....b+ seems to be low? Power supply pin 10 to 9 is 187v and pin 10 to pin 8 is 76v and pin 10 to pin 7 is 18v

6/2/2003 11:31:28 AMsean

Hello just measured speaker field coil voltage...its 110 volts.
:Hello, I tested 71a tube voltages. from pin 1 to pin 2 is 75 volts. from pin 1 to pin 3 is -13.95v.....b+ seems to be low? Power supply pin 10 to 9 is 187v and pin 10 to pin 8 is 76v and pin 10 to pin 7 is 18v

6/2/2003 11:50:54 AMsean

Hello I just swapped the 80 tube just to see....no change

:
:Hello just measured speaker field coil voltage...its 110 volts.
::Hello, I tested 71a tube voltages. from pin 1 to pin 2 is 75 volts. from pin 1 to pin 3 is -13.95v.....b+ seems to be low? Power supply pin 10 to 9 is 187v and pin 10 to pin 8 is 76v and pin 10 to pin 7 is 18v

6/2/2003 11:55:16 AMsean

Hello, forgot to measure plate to filament.....74.6volts each

:Hello I just swapped the 80 tube just to see....no change
:
::
::Hello just measured speaker field coil voltage...its 110 volts.
:::Hello, I tested 71a tube voltages. from pin 1 to pin 2 is 75 volts. from pin 1 to pin 3 is -13.95v.....b+ seems to be low? Power supply pin 10 to 9 is 187v and pin 10 to pin 8 is 76v and pin 10 to pin 7 is 18v

6/2/2003 12:01:57 PMsean

Hello measures grid to filament...its 13.74..so these tubes are good then?...they seem to be almost exact in voltage measurements so is that how they would be called a matched pair...I was wondering why tubes have to be matched

:Hello, forgot to measure plate to filament.....74.6volts each
:
::Hello I just swapped the 80 tube just to see....no change
::
:::
:::Hello just measured speaker field coil voltage...its 110 volts.
::::Hello, I tested 71a tube voltages. from pin 1 to pin 2 is 75 volts. from pin 1 to pin 3 is -13.95v.....b+ seems to be low? Power supply pin 10 to 9 is 187v and pin 10 to pin 8 is 76v and pin 10 to pin 7 is 18v

6/2/2003 12:02:11 PMsean

Hello measures grid to filament...its 13.74..so these tubes are good then?...they seem to be almost exact in voltage measurements so is that how they would be called a matched pair...I was wondering why tubes have to be matched

:Hello, forgot to measure plate to filament.....74.6volts each
:
::Hello I just swapped the 80 tube just to see....no change
::
:::
:::Hello just measured speaker field coil voltage...its 110 volts.
::::Hello, I tested 71a tube voltages. from pin 1 to pin 2 is 75 volts. from pin 1 to pin 3 is -13.95v.....b+ seems to be low? Power supply pin 10 to 9 is 187v and pin 10 to pin 8 is 76v and pin 10 to pin 7 is 18v

6/2/2003 12:16:09 PMNorm Leal

Sean

Plate voltage on your 71A's is too low. This will cause distortion with high volume. Why is your voltage so low?

What voltage do you have on pin #1 of the 80? This will be highest in your radio. The highest you mentioned is 187 volts. Since 110 volts is dropped across the field this would leave 77 volts, not enough.

Voltage will the same on both 71A's even if they aren't matched. For voltage measurement these tubes are tied together. If you were to remove one and measure both tubes pins they would still seem matched, even though one tube was pulled.

Norm

:Hello measures grid to filament...its 13.74..so these tubes are good then?...they seem to be almost exact in voltage measurements so is that how they would be called a matched pair...I was wondering why tubes have to be matched
:
::Hello, forgot to measure plate to filament.....74.6volts each
::
:::Hello I just swapped the 80 tube just to see....no change
:::
::::
::::Hello just measured speaker field coil voltage...its 110 volts.
:::::Hello, I tested 71a tube voltages. from pin 1 to pin 2 is 75 volts. from pin 1 to pin 3 is -13.95v.....b+ seems to be low? Power supply pin 10 to 9 is 187v and pin 10 to pin 8 is 76v and pin 10 to pin 7 is 18v

6/2/2003 12:37:44 PMsean

Hello, no load voltage is 305 on pin 9 to pin 10. pin 1 of 80 to pin 10 of terminals is 229 volts. All of the previous readings were with the hi lo switch in the low position. So the 80 measurement in the lo position would be 208 volts...I HOPE THIS IS NOT ANOTHER BAD TRANS..SINCE THIS THING IS HUGE

:Sean
:
: Plate voltage on your 71A's is too low. This will cause distortion with high volume. Why is your voltage so low?
:
: What voltage do you have on pin #1 of the 80? This will be highest in your radio. The highest you mentioned is 187 volts. Since 110 volts is dropped across the field this would leave 77 volts, not enough.
:
: Voltage will the same on both 71A's even if they aren't matched. For voltage measurement these tubes are tied together. If you were to remove one and measure both tubes pins they would still seem matched, even though one tube was pulled.
:
:Norm
:
::Hello measures grid to filament...its 13.74..so these tubes are good then?...they seem to be almost exact in voltage measurements so is that how they would be called a matched pair...I was wondering why tubes have to be matched
::
:::Hello, forgot to measure plate to filament.....74.6volts each
:::
::::Hello I just swapped the 80 tube just to see....no change
::::
:::::
:::::Hello just measured speaker field coil voltage...its 110 volts.
::::::Hello, I tested 71a tube voltages. from pin 1 to pin 2 is 75 volts. from pin 1 to pin 3 is -13.95v.....b+ seems to be low? Power supply pin 10 to 9 is 187v and pin 10 to pin 8 is 76v and pin 10 to pin 7 is 18v

6/2/2003 12:40:16 PMsean

Hello I just switched the meter to a/c and it reads 118 volts at pin 1 of the 80 to pin 10 of terminals......bad cap maybe?

:Hello, no load voltage is 305 on pin 9 to pin 10. pin 1 of 80 to pin 10 of terminals is 229 volts. All of the previous readings were with the hi lo switch in the low position. So the 80 measurement in the lo position would be 208 volts...I HOPE THIS IS NOT ANOTHER BAD TRANS..SINCE THIS THING IS HUGE
:
::Sean
::
:: Plate voltage on your 71A's is too low. This will cause distortion with high volume. Why is your voltage so low?
::
:: What voltage do you have on pin #1 of the 80? This will be highest in your radio. The highest you mentioned is 187 volts. Since 110 volts is dropped across the field this would leave 77 volts, not enough.
::
:: Voltage will the same on both 71A's even if they aren't matched. For voltage measurement these tubes are tied together. If you were to remove one and measure both tubes pins they would still seem matched, even though one tube was pulled.
::
::Norm
::
:::Hello measures grid to filament...its 13.74..so these tubes are good then?...they seem to be almost exact in voltage measurements so is that how they would be called a matched pair...I was wondering why tubes have to be matched
:::
::::Hello, forgot to measure plate to filament.....74.6volts each
::::
:::::Hello I just swapped the 80 tube just to see....no change
:::::
::::::
::::::Hello just measured speaker field coil voltage...its 110 volts.
:::::::Hello, I tested 71a tube voltages. from pin 1 to pin 2 is 75 volts. from pin 1 to pin 3 is -13.95v.....b+ seems to be low? Power supply pin 10 to 9 is 187v and pin 10 to pin 8 is 76v and pin 10 to pin 7 is 18v

6/2/2003 2:25:46 PMNorm Leal

Sean

Not a bad power transformer. A bad power transformer would be smoking..

Since I don't know the circuit pin numbers don't mean much. You seem to have good voltages. Voltage from pin 1 of the 80 to chassis will be DC.

If your speaker field drops 110 volts and you have 305 in the radio where does the rest go? That leaves 195 volts, plenty for the 71A circuit.

Norm

:Hello I just switched the meter to a/c and it reads 118 volts at pin 1 of the 80 to pin 10 of terminals......bad cap maybe?
:
::Hello, no load voltage is 305 on pin 9 to pin 10. pin 1 of 80 to pin 10 of terminals is 229 volts. All of the previous readings were with the hi lo switch in the low position. So the 80 measurement in the lo position would be 208 volts...I HOPE THIS IS NOT ANOTHER BAD TRANS..SINCE THIS THING IS HUGE
::
:::Sean
:::
::: Plate voltage on your 71A's is too low. This will cause distortion with high volume. Why is your voltage so low?
:::
::: What voltage do you have on pin #1 of the 80? This will be highest in your radio. The highest you mentioned is 187 volts. Since 110 volts is dropped across the field this would leave 77 volts, not enough.
:::
::: Voltage will the same on both 71A's even if they aren't matched. For voltage measurement these tubes are tied together. If you were to remove one and measure both tubes pins they would still seem matched, even though one tube was pulled.
:::
:::Norm
:::
::::Hello measures grid to filament...its 13.74..so these tubes are good then?...they seem to be almost exact in voltage measurements so is that how they would be called a matched pair...I was wondering why tubes have to be matched
::::
:::::Hello, forgot to measure plate to filament.....74.6volts each
:::::
::::::Hello I just swapped the 80 tube just to see....no change
::::::
:::::::
:::::::Hello just measured speaker field coil voltage...its 110 volts.
::::::::Hello, I tested 71a tube voltages. from pin 1 to pin 2 is 75 volts. from pin 1 to pin 3 is -13.95v.....b+ seems to be low? Power supply pin 10 to 9 is 187v and pin 10 to pin 8 is 76v and pin 10 to pin 7 is 18v

6/2/2003 2:36:13 PMsean

hello, the 305 volts is with no load, with load b+ drops to 187 at the power supply. I would assume all voltages are measured from pin one of the 71a. I just measured from plate to chassis ground and it is 82 volts

:Sean
:
: Not a bad power transformer. A bad power transformer would be smoking..
:
: Since I don't know the circuit pin numbers don't mean much. You seem to have good voltages. Voltage from pin 1 of the 80 to chassis will be DC.
:
: If your speaker field drops 110 volts and you have 305 in the radio where does the rest go? That leaves 195 volts, plenty for the 71A circuit.
:
:Norm
:
:
::Hello I just switched the meter to a/c and it reads 118 volts at pin 1 of the 80 to pin 10 of terminals......bad cap maybe?
::
:::Hello, no load voltage is 305 on pin 9 to pin 10. pin 1 of 80 to pin 10 of terminals is 229 volts. All of the previous readings were with the hi lo switch in the low position. So the 80 measurement in the lo position would be 208 volts...I HOPE THIS IS NOT ANOTHER BAD TRANS..SINCE THIS THING IS HUGE
:::
::::Sean
::::
:::: Plate voltage on your 71A's is too low. This will cause distortion with high volume. Why is your voltage so low?
::::
:::: What voltage do you have on pin #1 of the 80? This will be highest in your radio. The highest you mentioned is 187 volts. Since 110 volts is dropped across the field this would leave 77 volts, not enough.
::::
:::: Voltage will the same on both 71A's even if they aren't matched. For voltage measurement these tubes are tied together. If you were to remove one and measure both tubes pins they would still seem matched, even though one tube was pulled.
::::
::::Norm
::::
:::::Hello measures grid to filament...its 13.74..so these tubes are good then?...they seem to be almost exact in voltage measurements so is that how they would be called a matched pair...I was wondering why tubes have to be matched
:::::
::::::Hello, forgot to measure plate to filament.....74.6volts each
::::::
:::::::Hello I just swapped the 80 tube just to see....no change
:::::::
::::::::
::::::::Hello just measured speaker field coil voltage...its 110 volts.
:::::::::Hello, I tested 71a tube voltages. from pin 1 to pin 2 is 75 volts. from pin 1 to pin 3 is -13.95v.....b+ seems to be low? Power supply pin 10 to 9 is 187v and pin 10 to pin 8 is 76v and pin 10 to pin 7 is 18v

6/2/2003 2:49:27 PMsean

Hello, I just thought I would try a 10 uf cap to see if voltage rose any..didnt do anything except get rid of what little hum it had. The radio seems to be VERY close to a us radio model 80. The schematic even shows the terminals my power supply has. voltages match too. The power supply shows resistors in it, could they have drifted in value only showing up under load?

:hello, the 305 volts is with no load, with load b+ drops to 187 at the power supply. I would assume all voltages are measured from pin one of the 71a. I just measured from plate to chassis ground and it is 82 volts
:
::Sean
::
:: Not a bad power transformer. A bad power transformer would be smoking..
::
:: Since I don't know the circuit pin numbers don't mean much. You seem to have good voltages. Voltage from pin 1 of the 80 to chassis will be DC.
::
:: If your speaker field drops 110 volts and you have 305 in the radio where does the rest go? That leaves 195 volts, plenty for the 71A circuit.
::
::Norm
::
::
:::Hello I just switched the meter to a/c and it reads 118 volts at pin 1 of the 80 to pin 10 of terminals......bad cap maybe?
:::
::::Hello, no load voltage is 305 on pin 9 to pin 10. pin 1 of 80 to pin 10 of terminals is 229 volts. All of the previous readings were with the hi lo switch in the low position. So the 80 measurement in the lo position would be 208 volts...I HOPE THIS IS NOT ANOTHER BAD TRANS..SINCE THIS THING IS HUGE
::::
:::::Sean
:::::
::::: Plate voltage on your 71A's is too low. This will cause distortion with high volume. Why is your voltage so low?
:::::
::::: What voltage do you have on pin #1 of the 80? This will be highest in your radio. The highest you mentioned is 187 volts. Since 110 volts is dropped across the field this would leave 77 volts, not enough.
:::::
::::: Voltage will the same on both 71A's even if they aren't matched. For voltage measurement these tubes are tied together. If you were to remove one and measure both tubes pins they would still seem matched, even though one tube was pulled.
:::::
:::::Norm
:::::
::::::Hello measures grid to filament...its 13.74..so these tubes are good then?...they seem to be almost exact in voltage measurements so is that how they would be called a matched pair...I was wondering why tubes have to be matched
::::::
:::::::Hello, forgot to measure plate to filament.....74.6volts each
:::::::
::::::::Hello I just swapped the 80 tube just to see....no change
::::::::
:::::::::
:::::::::Hello just measured speaker field coil voltage...its 110 volts.
::::::::::Hello, I tested 71a tube voltages. from pin 1 to pin 2 is 75 volts. from pin 1 to pin 3 is -13.95v.....b+ seems to be low? Power supply pin 10 to 9 is 187v and pin 10 to pin 8 is 76v and pin 10 to pin 7 is 18v

6/2/2003 2:59:06 PMsean

Hello, I just measured speaker field coil ma.........37ma.....I would think it should be at least 60ma....all the tube plate ma added up. the tube chart for the 71a lists 180 and 80 volts plate voltage. could this radio only need 80 volts plate on 71a?

:Hello, I just thought I would try a 10 uf cap to see if voltage rose any..didnt do anything except get rid of what little hum it had. The radio seems to be VERY close to a us radio model 80. The schematic even shows the terminals my power supply has. voltages match too. The power supply shows resistors in it, could they have drifted in value only showing up under load?
:
::hello, the 305 volts is with no load, with load b+ drops to 187 at the power supply. I would assume all voltages are measured from pin one of the 71a. I just measured from plate to chassis ground and it is 82 volts
::
:::Sean
:::
::: Not a bad power transformer. A bad power transformer would be smoking..
:::
::: Since I don't know the circuit pin numbers don't mean much. You seem to have good voltages. Voltage from pin 1 of the 80 to chassis will be DC.
:::
::: If your speaker field drops 110 volts and you have 305 in the radio where does the rest go? That leaves 195 volts, plenty for the 71A circuit.
:::
:::Norm
:::
:::
::::Hello I just switched the meter to a/c and it reads 118 volts at pin 1 of the 80 to pin 10 of terminals......bad cap maybe?
::::
:::::Hello, no load voltage is 305 on pin 9 to pin 10. pin 1 of 80 to pin 10 of terminals is 229 volts. All of the previous readings were with the hi lo switch in the low position. So the 80 measurement in the lo position would be 208 volts...I HOPE THIS IS NOT ANOTHER BAD TRANS..SINCE THIS THING IS HUGE
:::::
::::::Sean
::::::
:::::: Plate voltage on your 71A's is too low. This will cause distortion with high volume. Why is your voltage so low?
::::::
:::::: What voltage do you have on pin #1 of the 80? This will be highest in your radio. The highest you mentioned is 187 volts. Since 110 volts is dropped across the field this would leave 77 volts, not enough.
::::::
:::::: Voltage will the same on both 71A's even if they aren't matched. For voltage measurement these tubes are tied together. If you were to remove one and measure both tubes pins they would still seem matched, even though one tube was pulled.
::::::
::::::Norm
::::::
:::::::Hello measures grid to filament...its 13.74..so these tubes are good then?...they seem to be almost exact in voltage measurements so is that how they would be called a matched pair...I was wondering why tubes have to be matched
:::::::
::::::::Hello, forgot to measure plate to filament.....74.6volts each
::::::::
:::::::::Hello I just swapped the 80 tube just to see....no change
:::::::::
::::::::::
::::::::::Hello just measured speaker field coil voltage...its 110 volts.
:::::::::::Hello, I tested 71a tube voltages. from pin 1 to pin 2 is 75 volts. from pin 1 to pin 3 is -13.95v.....b+ seems to be low? Power supply pin 10 to 9 is 187v and pin 10 to pin 8 is 76v and pin 10 to pin 7 is 18v

6/2/2003 3:08:07 PMNorm Leal

Hi Sean

Notice the voltage chart for US Radio Model 80. Voltages are way higher than your radio.

For a test add a 1000-2000 ohm 10 watt resistor across your field. See if this helps?

Your overall current is low because voltage is also low. When voltage is higher tubes will draw more current.

Norm

:Hello, I just measured speaker field coil ma.........37ma.....I would think it should be at least 60ma....all the tube plate ma added up. the tube chart for the 71a lists 180 and 80 volts plate voltage. could this radio only need 80 volts plate on 71a?
:
::Hello, I just thought I would try a 10 uf cap to see if voltage rose any..didnt do anything except get rid of what little hum it had. The radio seems to be VERY close to a us radio model 80. The schematic even shows the terminals my power supply has. voltages match too. The power supply shows resistors in it, could they have drifted in value only showing up under load?
::
:::hello, the 305 volts is with no load, with load b+ drops to 187 at the power supply. I would assume all voltages are measured from pin one of the 71a. I just measured from plate to chassis ground and it is 82 volts
:::
::::Sean
::::
:::: Not a bad power transformer. A bad power transformer would be smoking..
::::
:::: Since I don't know the circuit pin numbers don't mean much. You seem to have good voltages. Voltage from pin 1 of the 80 to chassis will be DC.
::::
:::: If your speaker field drops 110 volts and you have 305 in the radio where does the rest go? That leaves 195 volts, plenty for the 71A circuit.
::::
::::Norm
::::
::::
:::::Hello I just switched the meter to a/c and it reads 118 volts at pin 1 of the 80 to pin 10 of terminals......bad cap maybe?
:::::
::::::Hello, no load voltage is 305 on pin 9 to pin 10. pin 1 of 80 to pin 10 of terminals is 229 volts. All of the previous readings were with the hi lo switch in the low position. So the 80 measurement in the lo position would be 208 volts...I HOPE THIS IS NOT ANOTHER BAD TRANS..SINCE THIS THING IS HUGE
::::::
:::::::Sean
:::::::
::::::: Plate voltage on your 71A's is too low. This will cause distortion with high volume. Why is your voltage so low?
:::::::
::::::: What voltage do you have on pin #1 of the 80? This will be highest in your radio. The highest you mentioned is 187 volts. Since 110 volts is dropped across the field this would leave 77 volts, not enough.
:::::::
::::::: Voltage will the same on both 71A's even if they aren't matched. For voltage measurement these tubes are tied together. If you were to remove one and measure both tubes pins they would still seem matched, even though one tube was pulled.
:::::::
:::::::Norm
:::::::
::::::::Hello measures grid to filament...its 13.74..so these tubes are good then?...they seem to be almost exact in voltage measurements so is that how they would be called a matched pair...I was wondering why tubes have to be matched
::::::::
:::::::::Hello, forgot to measure plate to filament.....74.6volts each
:::::::::
::::::::::Hello I just swapped the 80 tube just to see....no change
::::::::::
:::::::::::
:::::::::::Hello just measured speaker field coil voltage...its 110 volts.
::::::::::::Hello, I tested 71a tube voltages. from pin 1 to pin 2 is 75 volts. from pin 1 to pin 3 is -13.95v.....b+ seems to be low? Power supply pin 10 to 9 is 187v and pin 10 to pin 8 is 76v and pin 10 to pin 7 is 18v

6/2/2003 3:33:26 PMsean

Hello, I put a 2.5 kohm on and voltage jumps up to 100v plate on 71a. Overall B+ drops from 187 to 180. I got the 305 volts b+ by dissconnecting the radio from the power supply

:Hi Sean
:
: Notice the voltage chart for US Radio Model 80. Voltages are way higher than your radio.
:
: For a test add a 1000-2000 ohm 10 watt resistor across your field. See if this helps?
:
: Your overall current is low because voltage is also low. When voltage is higher tubes will draw more current.
:
:Norm
:
:
::Hello, I just measured speaker field coil ma.........37ma.....I would think it should be at least 60ma....all the tube plate ma added up. the tube chart for the 71a lists 180 and 80 volts plate voltage. could this radio only need 80 volts plate on 71a?
::
:::Hello, I just thought I would try a 10 uf cap to see if voltage rose any..didnt do anything except get rid of what little hum it had. The radio seems to be VERY close to a us radio model 80. The schematic even shows the terminals my power supply has. voltages match too. The power supply shows resistors in it, could they have drifted in value only showing up under load?
:::
::::hello, the 305 volts is with no load, with load b+ drops to 187 at the power supply. I would assume all voltages are measured from pin one of the 71a. I just measured from plate to chassis ground and it is 82 volts
::::
:::::Sean
:::::
::::: Not a bad power transformer. A bad power transformer would be smoking..
:::::
::::: Since I don't know the circuit pin numbers don't mean much. You seem to have good voltages. Voltage from pin 1 of the 80 to chassis will be DC.
:::::
::::: If your speaker field drops 110 volts and you have 305 in the radio where does the rest go? That leaves 195 volts, plenty for the 71A circuit.
:::::
:::::Norm
:::::
:::::
::::::Hello I just switched the meter to a/c and it reads 118 volts at pin 1 of the 80 to pin 10 of terminals......bad cap maybe?
::::::
:::::::Hello, no load voltage is 305 on pin 9 to pin 10. pin 1 of 80 to pin 10 of terminals is 229 volts. All of the previous readings were with the hi lo switch in the low position. So the 80 measurement in the lo position would be 208 volts...I HOPE THIS IS NOT ANOTHER BAD TRANS..SINCE THIS THING IS HUGE
:::::::
::::::::Sean
::::::::
:::::::: Plate voltage on your 71A's is too low. This will cause distortion with high volume. Why is your voltage so low?
::::::::
:::::::: What voltage do you have on pin #1 of the 80? This will be highest in your radio. The highest you mentioned is 187 volts. Since 110 volts is dropped across the field this would leave 77 volts, not enough.
::::::::
:::::::: Voltage will the same on both 71A's even if they aren't matched. For voltage measurement these tubes are tied together. If you were to remove one and measure both tubes pins they would still seem matched, even though one tube was pulled.
::::::::
::::::::Norm
::::::::
:::::::::Hello measures grid to filament...its 13.74..so these tubes are good then?...they seem to be almost exact in voltage measurements so is that how they would be called a matched pair...I was wondering why tubes have to be matched
:::::::::
::::::::::Hello, forgot to measure plate to filament.....74.6volts each
::::::::::
:::::::::::Hello I just swapped the 80 tube just to see....no change
:::::::::::
::::::::::::
::::::::::::Hello just measured speaker field coil voltage...its 110 volts.
:::::::::::::Hello, I tested 71a tube voltages. from pin 1 to pin 2 is 75 volts. from pin 1 to pin 3 is -13.95v.....b+ seems to be low? Power supply pin 10 to 9 is 187v and pin 10 to pin 8 is 76v and pin 10 to pin 7 is 18v

6/2/2003 3:46:15 PMsean

:Hello, I am thinking the power supply is not high enough for some reason or the speaker field coil is too high in resistance
:
:Hello, I put a 2.5 kohm on and voltage jumps up to 100v plate on 71a. Overall B+ drops from 187 to 180. I got the 305 volts b+ by dissconnecting the radio from the power supply
:
::Hi Sean
::
:: Notice the voltage chart for US Radio Model 80. Voltages are way higher than your radio.
::
:: For a test add a 1000-2000 ohm 10 watt resistor across your field. See if this helps?
::
:: Your overall current is low because voltage is also low. When voltage is higher tubes will draw more current.
::
::Norm
::
::
:::Hello, I just measured speaker field coil ma.........37ma.....I would think it should be at least 60ma....all the tube plate ma added up. the tube chart for the 71a lists 180 and 80 volts plate voltage. could this radio only need 80 volts plate on 71a?
:::
::::Hello, I just thought I would try a 10 uf cap to see if voltage rose any..didnt do anything except get rid of what little hum it had. The radio seems to be VERY close to a us radio model 80. The schematic even shows the terminals my power supply has. voltages match too. The power supply shows resistors in it, could they have drifted in value only showing up under load?
::::
:::::hello, the 305 volts is with no load, with load b+ drops to 187 at the power supply. I would assume all voltages are measured from pin one of the 71a. I just measured from plate to chassis ground and it is 82 volts
:::::
::::::Sean
::::::
:::::: Not a bad power transformer. A bad power transformer would be smoking..
::::::
:::::: Since I don't know the circuit pin numbers don't mean much. You seem to have good voltages. Voltage from pin 1 of the 80 to chassis will be DC.
::::::
:::::: If your speaker field drops 110 volts and you have 305 in the radio where does the rest go? That leaves 195 volts, plenty for the 71A circuit.
::::::
::::::Norm
::::::
::::::
:::::::Hello I just switched the meter to a/c and it reads 118 volts at pin 1 of the 80 to pin 10 of terminals......bad cap maybe?
:::::::
::::::::Hello, no load voltage is 305 on pin 9 to pin 10. pin 1 of 80 to pin 10 of terminals is 229 volts. All of the previous readings were with the hi lo switch in the low position. So the 80 measurement in the lo position would be 208 volts...I HOPE THIS IS NOT ANOTHER BAD TRANS..SINCE THIS THING IS HUGE
::::::::
:::::::::Sean
:::::::::
::::::::: Plate voltage on your 71A's is too low. This will cause distortion with high volume. Why is your voltage so low?
:::::::::
::::::::: What voltage do you have on pin #1 of the 80? This will be highest in your radio. The highest you mentioned is 187 volts. Since 110 volts is dropped across the field this would leave 77 volts, not enough.
:::::::::
::::::::: Voltage will the same on both 71A's even if they aren't matched. For voltage measurement these tubes are tied together. If you were to remove one and measure both tubes pins they would still seem matched, even though one tube was pulled.
:::::::::
:::::::::Norm
:::::::::
::::::::::Hello measures grid to filament...its 13.74..so these tubes are good then?...they seem to be almost exact in voltage measurements so is that how they would be called a matched pair...I was wondering why tubes have to be matched
::::::::::
:::::::::::Hello, forgot to measure plate to filament.....74.6volts each
:::::::::::
::::::::::::Hello I just swapped the 80 tube just to see....no change
::::::::::::
:::::::::::::
:::::::::::::Hello just measured speaker field coil voltage...its 110 volts.
::::::::::::::Hello, I tested 71a tube voltages. from pin 1 to pin 2 is 75 volts. from pin 1 to pin 3 is -13.95v.....b+ seems to be low? Power supply pin 10 to 9 is 187v and pin 10 to pin 8 is 76v and pin 10 to pin 7 is 18v

6/2/2003 3:53:02 PMsean

Hello, If the power supply can put out 305v with no load, then it has to be good since it has no resistors in line with the B+, I thought there were but looked at schematic...there are none........interesting question is how much ma should this powersupply be able to handle?...100ma?

::Hello, I am thinking the power supply is not high enough for some reason or the speaker field coil is too high in resistance
::
::Hello, I put a 2.5 kohm on and voltage jumps up to 100v plate on 71a. Overall B+ drops from 187 to 180. I got the 305 volts b+ by dissconnecting the radio from the power supply
::
:::Hi Sean
:::
::: Notice the voltage chart for US Radio Model 80. Voltages are way higher than your radio.
:::
::: For a test add a 1000-2000 ohm 10 watt resistor across your field. See if this helps?
:::
::: Your overall current is low because voltage is also low. When voltage is higher tubes will draw more current.
:::
:::Norm
:::
:::
::::Hello, I just measured speaker field coil ma.........37ma.....I would think it should be at least 60ma....all the tube plate ma added up. the tube chart for the 71a lists 180 and 80 volts plate voltage. could this radio only need 80 volts plate on 71a?
::::
:::::Hello, I just thought I would try a 10 uf cap to see if voltage rose any..didnt do anything except get rid of what little hum it had. The radio seems to be VERY close to a us radio model 80. The schematic even shows the terminals my power supply has. voltages match too. The power supply shows resistors in it, could they have drifted in value only showing up under load?
:::::
::::::hello, the 305 volts is with no load, with load b+ drops to 187 at the power supply. I would assume all voltages are measured from pin one of the 71a. I just measured from plate to chassis ground and it is 82 volts
::::::
:::::::Sean
:::::::
::::::: Not a bad power transformer. A bad power transformer would be smoking..
:::::::
::::::: Since I don't know the circuit pin numbers don't mean much. You seem to have good voltages. Voltage from pin 1 of the 80 to chassis will be DC.
:::::::
::::::: If your speaker field drops 110 volts and you have 305 in the radio where does the rest go? That leaves 195 volts, plenty for the 71A circuit.
:::::::
:::::::Norm
:::::::
:::::::
::::::::Hello I just switched the meter to a/c and it reads 118 volts at pin 1 of the 80 to pin 10 of terminals......bad cap maybe?
::::::::
:::::::::Hello, no load voltage is 305 on pin 9 to pin 10. pin 1 of 80 to pin 10 of terminals is 229 volts. All of the previous readings were with the hi lo switch in the low position. So the 80 measurement in the lo position would be 208 volts...I HOPE THIS IS NOT ANOTHER BAD TRANS..SINCE THIS THING IS HUGE
:::::::::
::::::::::Sean
::::::::::
:::::::::: Plate voltage on your 71A's is too low. This will cause distortion with high volume. Why is your voltage so low?
::::::::::
:::::::::: What voltage do you have on pin #1 of the 80? This will be highest in your radio. The highest you mentioned is 187 volts. Since 110 volts is dropped across the field this would leave 77 volts, not enough.
::::::::::
:::::::::: Voltage will the same on both 71A's even if they aren't matched. For voltage measurement these tubes are tied together. If you were to remove one and measure both tubes pins they would still seem matched, even though one tube was pulled.
::::::::::
::::::::::Norm
::::::::::
:::::::::::Hello measures grid to filament...its 13.74..so these tubes are good then?...they seem to be almost exact in voltage measurements so is that how they would be called a matched pair...I was wondering why tubes have to be matched
:::::::::::
::::::::::::Hello, forgot to measure plate to filament.....74.6volts each
::::::::::::
:::::::::::::Hello I just swapped the 80 tube just to see....no change
:::::::::::::
::::::::::::::
::::::::::::::Hello just measured speaker field coil voltage...its 110 volts.
:::::::::::::::Hello, I tested 71a tube voltages. from pin 1 to pin 2 is 75 volts. from pin 1 to pin 3 is -13.95v.....b+ seems to be low? Power supply pin 10 to 9 is 187v and pin 10 to pin 8 is 76v and pin 10 to pin 7 is 18v

6/2/2003 4:01:24 PMNorm Leal

Sean

Voltage will be lower with a load. You could try another 80 or add a 10 mfd @ 450 volt from pin #1 of your 80 to chassis. Think you did both of these already.

Looks like your field is just too high in resistance. As you found a 3000 ohm field with 37 ma drops 110 volts.

A 1000 ohm field under the same load will drop 37 volts. This is 73 volt difference. This difference will be less because as voltage increases so does current.

Did the radio sound less distorted with a 2.5K resistor?

Norm
:Hello, If the power supply can put out 305v with no load, then it has to be good since it has no resistors in line with the B+, I thought there were but looked at schematic...there are none........interesting question is how much ma should this powersupply be able to handle?...100ma?
:
:::Hello, I am thinking the power supply is not high enough for some reason or the speaker field coil is too high in resistance
:::
:::Hello, I put a 2.5 kohm on and voltage jumps up to 100v plate on 71a. Overall B+ drops from 187 to 180. I got the 305 volts b+ by dissconnecting the radio from the power supply
:::
::::Hi Sean
::::
:::: Notice the voltage chart for US Radio Model 80. Voltages are way higher than your radio.
::::
:::: For a test add a 1000-2000 ohm 10 watt resistor across your field. See if this helps?
::::
:::: Your overall current is low because voltage is also low. When voltage is higher tubes will draw more current.
::::
::::Norm
::::
::::
:::::Hello, I just measured speaker field coil ma.........37ma.....I would think it should be at least 60ma....all the tube plate ma added up. the tube chart for the 71a lists 180 and 80 volts plate voltage. could this radio only need 80 volts plate on 71a?
:::::
::::::Hello, I just thought I would try a 10 uf cap to see if voltage rose any..didnt do anything except get rid of what little hum it had. The radio seems to be VERY close to a us radio model 80. The schematic even shows the terminals my power supply has. voltages match too. The power supply shows resistors in it, could they have drifted in value only showing up under load?
::::::
:::::::hello, the 305 volts is with no load, with load b+ drops to 187 at the power supply. I would assume all voltages are measured from pin one of the 71a. I just measured from plate to chassis ground and it is 82 volts
:::::::
::::::::Sean
::::::::
:::::::: Not a bad power transformer. A bad power transformer would be smoking..
::::::::
:::::::: Since I don't know the circuit pin numbers don't mean much. You seem to have good voltages. Voltage from pin 1 of the 80 to chassis will be DC.
::::::::
:::::::: If your speaker field drops 110 volts and you have 305 in the radio where does the rest go? That leaves 195 volts, plenty for the 71A circuit.
::::::::
::::::::Norm
::::::::
::::::::
:::::::::Hello I just switched the meter to a/c and it reads 118 volts at pin 1 of the 80 to pin 10 of terminals......bad cap maybe?
:::::::::
::::::::::Hello, no load voltage is 305 on pin 9 to pin 10. pin 1 of 80 to pin 10 of terminals is 229 volts. All of the previous readings were with the hi lo switch in the low position. So the 80 measurement in the lo position would be 208 volts...I HOPE THIS IS NOT ANOTHER BAD TRANS..SINCE THIS THING IS HUGE
::::::::::
:::::::::::Sean
:::::::::::
::::::::::: Plate voltage on your 71A's is too low. This will cause distortion with high volume. Why is your voltage so low?
:::::::::::
::::::::::: What voltage do you have on pin #1 of the 80? This will be highest in your radio. The highest you mentioned is 187 volts. Since 110 volts is dropped across the field this would leave 77 volts, not enough.
:::::::::::
::::::::::: Voltage will the same on both 71A's even if they aren't matched. For voltage measurement these tubes are tied together. If you were to remove one and measure both tubes pins they would still seem matched, even though one tube was pulled.
:::::::::::
:::::::::::Norm
:::::::::::
::::::::::::Hello measures grid to filament...its 13.74..so these tubes are good then?...they seem to be almost exact in voltage measurements so is that how they would be called a matched pair...I was wondering why tubes have to be matched
::::::::::::
:::::::::::::Hello, forgot to measure plate to filament.....74.6volts each
:::::::::::::
::::::::::::::Hello I just swapped the 80 tube just to see....no change
::::::::::::::
:::::::::::::::
:::::::::::::::Hello just measured speaker field coil voltage...its 110 volts.
::::::::::::::::Hello, I tested 71a tube voltages. from pin 1 to pin 2 is 75 volts. from pin 1 to pin 3 is -13.95v.....b+ seems to be low? Power supply pin 10 to 9 is 187v and pin 10 to pin 8 is 76v and pin 10 to pin 7 is 18v

6/2/2003 4:06:31 PMsean

Hello, yes the radio did sound less distorted, more clearer even at lower volumes. So what should I do? Keep the speaker and add resistance in parallel or just get another speaker?

:Sean
:
: Voltage will be lower with a load. You could try another 80 or add a 10 mfd @ 450 volt from pin #1 of your 80 to chassis. Think you did both of these already.
:
: Looks like your field is just too high in resistance. As you found a 3000 ohm field with 37 ma drops 110 volts.
:
: A 1000 ohm field under the same load will drop 37 volts. This is 73 volt difference. This difference will be less because as voltage increases so does current.
:
: Did the radio sound less distorted with a 2.5K resistor?
:
:Norm
::Hello, If the power supply can put out 305v with no load, then it has to be good since it has no resistors in line with the B+, I thought there were but looked at schematic...there are none........interesting question is how much ma should this powersupply be able to handle?...100ma?
::
::::Hello, I am thinking the power supply is not high enough for some reason or the speaker field coil is too high in resistance
::::
::::Hello, I put a 2.5 kohm on and voltage jumps up to 100v plate on 71a. Overall B+ drops from 187 to 180. I got the 305 volts b+ by dissconnecting the radio from the power supply
::::
:::::Hi Sean
:::::
::::: Notice the voltage chart for US Radio Model 80. Voltages are way higher than your radio.
:::::
::::: For a test add a 1000-2000 ohm 10 watt resistor across your field. See if this helps?
:::::
::::: Your overall current is low because voltage is also low. When voltage is higher tubes will draw more current.
:::::
:::::Norm
:::::
:::::
::::::Hello, I just measured speaker field coil ma.........37ma.....I would think it should be at least 60ma....all the tube plate ma added up. the tube chart for the 71a lists 180 and 80 volts plate voltage. could this radio only need 80 volts plate on 71a?
::::::
:::::::Hello, I just thought I would try a 10 uf cap to see if voltage rose any..didnt do anything except get rid of what little hum it had. The radio seems to be VERY close to a us radio model 80. The schematic even shows the terminals my power supply has. voltages match too. The power supply shows resistors in it, could they have drifted in value only showing up under load?
:::::::
::::::::hello, the 305 volts is with no load, with load b+ drops to 187 at the power supply. I would assume all voltages are measured from pin one of the 71a. I just measured from plate to chassis ground and it is 82 volts
::::::::
:::::::::Sean
:::::::::
::::::::: Not a bad power transformer. A bad power transformer would be smoking..
:::::::::
::::::::: Since I don't know the circuit pin numbers don't mean much. You seem to have good voltages. Voltage from pin 1 of the 80 to chassis will be DC.
:::::::::
::::::::: If your speaker field drops 110 volts and you have 305 in the radio where does the rest go? That leaves 195 volts, plenty for the 71A circuit.
:::::::::
:::::::::Norm
:::::::::
:::::::::
::::::::::Hello I just switched the meter to a/c and it reads 118 volts at pin 1 of the 80 to pin 10 of terminals......bad cap maybe?
::::::::::
:::::::::::Hello, no load voltage is 305 on pin 9 to pin 10. pin 1 of 80 to pin 10 of terminals is 229 volts. All of the previous readings were with the hi lo switch in the low position. So the 80 measurement in the lo position would be 208 volts...I HOPE THIS IS NOT ANOTHER BAD TRANS..SINCE THIS THING IS HUGE
:::::::::::
::::::::::::Sean
::::::::::::
:::::::::::: Plate voltage on your 71A's is too low. This will cause distortion with high volume. Why is your voltage so low?
::::::::::::
:::::::::::: What voltage do you have on pin #1 of the 80? This will be highest in your radio. The highest you mentioned is 187 volts. Since 110 volts is dropped across the field this would leave 77 volts, not enough.
::::::::::::
:::::::::::: Voltage will the same on both 71A's even if they aren't matched. For voltage measurement these tubes are tied together. If you were to remove one and measure both tubes pins they would still seem matched, even though one tube was pulled.
::::::::::::
::::::::::::Norm
::::::::::::
:::::::::::::Hello measures grid to filament...its 13.74..so these tubes are good then?...they seem to be almost exact in voltage measurements so is that how they would be called a matched pair...I was wondering why tubes have to be matched
:::::::::::::
::::::::::::::Hello, forgot to measure plate to filament.....74.6volts each
::::::::::::::
:::::::::::::::Hello I just swapped the 80 tube just to see....no change
:::::::::::::::
::::::::::::::::
::::::::::::::::Hello just measured speaker field coil voltage...its 110 volts.
:::::::::::::::::Hello, I tested 71a tube voltages. from pin 1 to pin 2 is 75 volts. from pin 1 to pin 3 is -13.95v.....b+ seems to be low? Power supply pin 10 to 9 is 187v and pin 10 to pin 8 is 76v and pin 10 to pin 7 is 18v

6/2/2003 4:08:49 PMsean

Hello, also as expected volume got louder with more plate voltage, so If I go with adding parallel resistance, do I add enough to get to 155 volts(I think its 155 volts according to the schematic chart, its so small in writing its hard to read.

:Hello, yes the radio did sound less distorted, more clearer even at lower volumes. So what should I do? Keep the speaker and add resistance in parallel or just get another speaker?
:
::Sean
::
:: Voltage will be lower with a load. You could try another 80 or add a 10 mfd @ 450 volt from pin #1 of your 80 to chassis. Think you did both of these already.
::
:: Looks like your field is just too high in resistance. As you found a 3000 ohm field with 37 ma drops 110 volts.
::
:: A 1000 ohm field under the same load will drop 37 volts. This is 73 volt difference. This difference will be less because as voltage increases so does current.
::
:: Did the radio sound less distorted with a 2.5K resistor?
::
::Norm
:::Hello, If the power supply can put out 305v with no load, then it has to be good since it has no resistors in line with the B+, I thought there were but looked at schematic...there are none........interesting question is how much ma should this powersupply be able to handle?...100ma?
:::
:::::Hello, I am thinking the power supply is not high enough for some reason or the speaker field coil is too high in resistance
:::::
:::::Hello, I put a 2.5 kohm on and voltage jumps up to 100v plate on 71a. Overall B+ drops from 187 to 180. I got the 305 volts b+ by dissconnecting the radio from the power supply
:::::
::::::Hi Sean
::::::
:::::: Notice the voltage chart for US Radio Model 80. Voltages are way higher than your radio.
::::::
:::::: For a test add a 1000-2000 ohm 10 watt resistor across your field. See if this helps?
::::::
:::::: Your overall current is low because voltage is also low. When voltage is higher tubes will draw more current.
::::::
::::::Norm
::::::
::::::
:::::::Hello, I just measured speaker field coil ma.........37ma.....I would think it should be at least 60ma....all the tube plate ma added up. the tube chart for the 71a lists 180 and 80 volts plate voltage. could this radio only need 80 volts plate on 71a?
:::::::
::::::::Hello, I just thought I would try a 10 uf cap to see if voltage rose any..didnt do anything except get rid of what little hum it had. The radio seems to be VERY close to a us radio model 80. The schematic even shows the terminals my power supply has. voltages match too. The power supply shows resistors in it, could they have drifted in value only showing up under load?
::::::::
:::::::::hello, the 305 volts is with no load, with load b+ drops to 187 at the power supply. I would assume all voltages are measured from pin one of the 71a. I just measured from plate to chassis ground and it is 82 volts
:::::::::
::::::::::Sean
::::::::::
:::::::::: Not a bad power transformer. A bad power transformer would be smoking..
::::::::::
:::::::::: Since I don't know the circuit pin numbers don't mean much. You seem to have good voltages. Voltage from pin 1 of the 80 to chassis will be DC.
::::::::::
:::::::::: If your speaker field drops 110 volts and you have 305 in the radio where does the rest go? That leaves 195 volts, plenty for the 71A circuit.
::::::::::
::::::::::Norm
::::::::::
::::::::::
:::::::::::Hello I just switched the meter to a/c and it reads 118 volts at pin 1 of the 80 to pin 10 of terminals......bad cap maybe?
:::::::::::
::::::::::::Hello, no load voltage is 305 on pin 9 to pin 10. pin 1 of 80 to pin 10 of terminals is 229 volts. All of the previous readings were with the hi lo switch in the low position. So the 80 measurement in the lo position would be 208 volts...I HOPE THIS IS NOT ANOTHER BAD TRANS..SINCE THIS THING IS HUGE
::::::::::::
:::::::::::::Sean
:::::::::::::
::::::::::::: Plate voltage on your 71A's is too low. This will cause distortion with high volume. Why is your voltage so low?
:::::::::::::
::::::::::::: What voltage do you have on pin #1 of the 80? This will be highest in your radio. The highest you mentioned is 187 volts. Since 110 volts is dropped across the field this would leave 77 volts, not enough.
:::::::::::::
::::::::::::: Voltage will the same on both 71A's even if they aren't matched. For voltage measurement these tubes are tied together. If you were to remove one and measure both tubes pins they would still seem matched, even though one tube was pulled.
:::::::::::::
:::::::::::::Norm
:::::::::::::
::::::::::::::Hello measures grid to filament...its 13.74..so these tubes are good then?...they seem to be almost exact in voltage measurements so is that how they would be called a matched pair...I was wondering why tubes have to be matched
::::::::::::::
:::::::::::::::Hello, forgot to measure plate to filament.....74.6volts each
:::::::::::::::
::::::::::::::::Hello I just swapped the 80 tube just to see....no change
::::::::::::::::
:::::::::::::::::
:::::::::::::::::Hello just measured speaker field coil voltage...its 110 volts.
::::::::::::::::::Hello, I tested 71a tube voltages. from pin 1 to pin 2 is 75 volts. from pin 1 to pin 3 is -13.95v.....b+ seems to be low? Power supply pin 10 to 9 is 187v and pin 10 to pin 8 is 76v and pin 10 to pin 7 is 18v

6/2/2003 5:49:19 PMNorm Leal

Sean

The right thing would be to have a lower resistance field. Putting a resistor across the field helps but at some point you won't have enough voltage to magnatize the core.

Here is another idea. Replace the field with a choke. Most chokes have much less resistance, around 300 ohms for 10 henries @ 70-90 ma.

Now you still need to power the field. Connect your speaker field from B+ to ground with a resistor in series, 5K @ 10 watts should work.

This will supply more voltage to your radio circuit and still power the field. Adjusting the resistor value controls voltage through the field.

Norm

:Hello, also as expected volume got louder with more plate voltage, so If I go with adding parallel resistance, do I add enough to get to 155 volts(I think its 155 volts according to the schematic chart, its so small in writing its hard to read.
:
::Hello, yes the radio did sound less distorted, more clearer even at lower volumes. So what should I do? Keep the speaker and add resistance in parallel or just get another speaker?
::
:::Sean
:::
::: Voltage will be lower with a load. You could try another 80 or add a 10 mfd @ 450 volt from pin #1 of your 80 to chassis. Think you did both of these already.
:::
::: Looks like your field is just too high in resistance. As you found a 3000 ohm field with 37 ma drops 110 volts.
:::
::: A 1000 ohm field under the same load will drop 37 volts. This is 73 volt difference. This difference will be less because as voltage increases so does current.
:::
::: Did the radio sound less distorted with a 2.5K resistor?
:::
:::Norm
::::Hello, If the power supply can put out 305v with no load, then it has to be good since it has no resistors in line with the B+, I thought there were but looked at schematic...there are none........interesting question is how much ma should this powersupply be able to handle?...100ma?
::::
::::::Hello, I am thinking the power supply is not high enough for some reason or the speaker field coil is too high in resistance
::::::
::::::Hello, I put a 2.5 kohm on and voltage jumps up to 100v plate on 71a. Overall B+ drops from 187 to 180. I got the 305 volts b+ by dissconnecting the radio from the power supply
::::::
:::::::Hi Sean
:::::::
::::::: Notice the voltage chart for US Radio Model 80. Voltages are way higher than your radio.
:::::::
::::::: For a test add a 1000-2000 ohm 10 watt resistor across your field. See if this helps?
:::::::
::::::: Your overall current is low because voltage is also low. When voltage is higher tubes will draw more current.
:::::::
:::::::Norm
:::::::
:::::::
::::::::Hello, I just measured speaker field coil ma.........37ma.....I would think it should be at least 60ma....all the tube plate ma added up. the tube chart for the 71a lists 180 and 80 volts plate voltage. could this radio only need 80 volts plate on 71a?
::::::::
:::::::::Hello, I just thought I would try a 10 uf cap to see if voltage rose any..didnt do anything except get rid of what little hum it had. The radio seems to be VERY close to a us radio model 80. The schematic even shows the terminals my power supply has. voltages match too. The power supply shows resistors in it, could they have drifted in value only showing up under load?
:::::::::
::::::::::hello, the 305 volts is with no load, with load b+ drops to 187 at the power supply. I would assume all voltages are measured from pin one of the 71a. I just measured from plate to chassis ground and it is 82 volts
::::::::::
:::::::::::Sean
:::::::::::
::::::::::: Not a bad power transformer. A bad power transformer would be smoking..
:::::::::::
::::::::::: Since I don't know the circuit pin numbers don't mean much. You seem to have good voltages. Voltage from pin 1 of the 80 to chassis will be DC.
:::::::::::
::::::::::: If your speaker field drops 110 volts and you have 305 in the radio where does the rest go? That leaves 195 volts, plenty for the 71A circuit.
:::::::::::
:::::::::::Norm
:::::::::::
:::::::::::
::::::::::::Hello I just switched the meter to a/c and it reads 118 volts at pin 1 of the 80 to pin 10 of terminals......bad cap maybe?
::::::::::::
:::::::::::::Hello, no load voltage is 305 on pin 9 to pin 10. pin 1 of 80 to pin 10 of terminals is 229 volts. All of the previous readings were with the hi lo switch in the low position. So the 80 measurement in the lo position would be 208 volts...I HOPE THIS IS NOT ANOTHER BAD TRANS..SINCE THIS THING IS HUGE
:::::::::::::
::::::::::::::Sean
::::::::::::::
:::::::::::::: Plate voltage on your 71A's is too low. This will cause distortion with high volume. Why is your voltage so low?
::::::::::::::
:::::::::::::: What voltage do you have on pin #1 of the 80? This will be highest in your radio. The highest you mentioned is 187 volts. Since 110 volts is dropped across the field this would leave 77 volts, not enough.
::::::::::::::
:::::::::::::: Voltage will the same on both 71A's even if they aren't matched. For voltage measurement these tubes are tied together. If you were to remove one and measure both tubes pins they would still seem matched, even though one tube was pulled.
::::::::::::::
::::::::::::::Norm
::::::::::::::
:::::::::::::::Hello measures grid to filament...its 13.74..so these tubes are good then?...they seem to be almost exact in voltage measurements so is that how they would be called a matched pair...I was wondering why tubes have to be matched
:::::::::::::::
::::::::::::::::Hello, forgot to measure plate to filament.....74.6volts each
::::::::::::::::
:::::::::::::::::Hello I just swapped the 80 tube just to see....no change
:::::::::::::::::
::::::::::::::::::
::::::::::::::::::Hello just measured speaker field coil voltage...its 110 volts.
:::::::::::::::::::Hello, I tested 71a tube voltages. from pin 1 to pin 2 is 75 volts. from pin 1 to pin 3 is -13.95v.....b+ seems to be low? Power supply pin 10 to 9 is 187v and pin 10 to pin 8 is 76v and pin 10 to pin 7 is 18v

6/2/2003 6:09:23 PMsean

Hello, I tried a 1kohm resistor and volume got louder. Power supply dropped to 151 volts. I just thought I would test the field coil resistance with my meter....it measured 3.27k ohms......wouldnt that be higher in the actual circuit with reactance? I'm not sure where I would get a 10 henry choke. I do have a 1950s(i think) TV that has chokes in it. Could I make one or is that too much of a bother. Original field was 1k..then why the less ohmage

:Sean
:
: The right thing would be to have a lower resistance field. Putting a resistor across the field helps but at some point you won't have enough voltage to magnatize the core.
:
: Here is another idea. Replace the field with a choke. Most chokes have much less resistance, around 300 ohms for 10 henries @ 70-90 ma.
:
: Now you still need to power the field. Connect your speaker field from B+ to ground with a resistor in series, 5K @ 10 watts should work.
:
: This will supply more voltage to your radio circuit and still power the field. Adjusting the resistor value controls voltage through the field.
:
:Norm
:
::Hello, also as expected volume got louder with more plate voltage, so If I go with adding parallel resistance, do I add enough to get to 155 volts(I think its 155 volts according to the schematic chart, its so small in writing its hard to read.
::
:::Hello, yes the radio did sound less distorted, more clearer even at lower volumes. So what should I do? Keep the speaker and add resistance in parallel or just get another speaker?
:::
::::Sean
::::
:::: Voltage will be lower with a load. You could try another 80 or add a 10 mfd @ 450 volt from pin #1 of your 80 to chassis. Think you did both of these already.
::::
:::: Looks like your field is just too high in resistance. As you found a 3000 ohm field with 37 ma drops 110 volts.
::::
:::: A 1000 ohm field under the same load will drop 37 volts. This is 73 volt difference. This difference will be less because as voltage increases so does current.
::::
:::: Did the radio sound less distorted with a 2.5K resistor?
::::
::::Norm
:::::Hello, If the power supply can put out 305v with no load, then it has to be good since it has no resistors in line with the B+, I thought there were but looked at schematic...there are none........interesting question is how much ma should this powersupply be able to handle?...100ma?
:::::
:::::::Hello, I am thinking the power supply is not high enough for some reason or the speaker field coil is too high in resistance
:::::::
:::::::Hello, I put a 2.5 kohm on and voltage jumps up to 100v plate on 71a. Overall B+ drops from 187 to 180. I got the 305 volts b+ by dissconnecting the radio from the power supply
:::::::
::::::::Hi Sean
::::::::
:::::::: Notice the voltage chart for US Radio Model 80. Voltages are way higher than your radio.
::::::::
:::::::: For a test add a 1000-2000 ohm 10 watt resistor across your field. See if this helps?
::::::::
:::::::: Your overall current is low because voltage is also low. When voltage is higher tubes will draw more current.
::::::::
::::::::Norm
::::::::
::::::::
:::::::::Hello, I just measured speaker field coil ma.........37ma.....I would think it should be at least 60ma....all the tube plate ma added up. the tube chart for the 71a lists 180 and 80 volts plate voltage. could this radio only need 80 volts plate on 71a?
:::::::::
::::::::::Hello, I just thought I would try a 10 uf cap to see if voltage rose any..didnt do anything except get rid of what little hum it had. The radio seems to be VERY close to a us radio model 80. The schematic even shows the terminals my power supply has. voltages match too. The power supply shows resistors in it, could they have drifted in value only showing up under load?
::::::::::
:::::::::::hello, the 305 volts is with no load, with load b+ drops to 187 at the power supply. I would assume all voltages are measured from pin one of the 71a. I just measured from plate to chassis ground and it is 82 volts
:::::::::::
::::::::::::Sean
::::::::::::
:::::::::::: Not a bad power transformer. A bad power transformer would be smoking..
::::::::::::
:::::::::::: Since I don't know the circuit pin numbers don't mean much. You seem to have good voltages. Voltage from pin 1 of the 80 to chassis will be DC.
::::::::::::
:::::::::::: If your speaker field drops 110 volts and you have 305 in the radio where does the rest go? That leaves 195 volts, plenty for the 71A circuit.
::::::::::::
::::::::::::Norm
::::::::::::
::::::::::::
:::::::::::::Hello I just switched the meter to a/c and it reads 118 volts at pin 1 of the 80 to pin 10 of terminals......bad cap maybe?
:::::::::::::
::::::::::::::Hello, no load voltage is 305 on pin 9 to pin 10. pin 1 of 80 to pin 10 of terminals is 229 volts. All of the previous readings were with the hi lo switch in the low position. So the 80 measurement in the lo position would be 208 volts...I HOPE THIS IS NOT ANOTHER BAD TRANS..SINCE THIS THING IS HUGE
::::::::::::::
:::::::::::::::Sean
:::::::::::::::
::::::::::::::: Plate voltage on your 71A's is too low. This will cause distortion with high volume. Why is your voltage so low?
:::::::::::::::
::::::::::::::: What voltage do you have on pin #1 of the 80? This will be highest in your radio. The highest you mentioned is 187 volts. Since 110 volts is dropped across the field this would leave 77 volts, not enough.
:::::::::::::::
::::::::::::::: Voltage will the same on both 71A's even if they aren't matched. For voltage measurement these tubes are tied together. If you were to remove one and measure both tubes pins they would still seem matched, even though one tube was pulled.
:::::::::::::::
:::::::::::::::Norm
:::::::::::::::
::::::::::::::::Hello measures grid to filament...its 13.74..so these tubes are good then?...they seem to be almost exact in voltage measurements so is that how they would be called a matched pair...I was wondering why tubes have to be matched
::::::::::::::::
:::::::::::::::::Hello, forgot to measure plate to filament.....74.6volts each
:::::::::::::::::
::::::::::::::::::Hello I just swapped the 80 tube just to see....no change
::::::::::::::::::
:::::::::::::::::::
:::::::::::::::::::Hello just measured speaker field coil voltage...its 110 volts.
::::::::::::::::::::Hello, I tested 71a tube voltages. from pin 1 to pin 2 is 75 volts. from pin 1 to pin 3 is -13.95v.....b+ seems to be low? Power supply pin 10 to 9 is 187v and pin 10 to pin 8 is 76v and pin 10 to pin 7 is 18v

6/2/2003 7:13:33 PMsean

Hello, I might have a 10 henry choke, but am not sure how to check it. About how big should a 10 henry choke be? I found one in the TV. Its a little over an inch square(dont know if that helps So if I put a 4.7k resistor in series with the field coil then I would draw about 25 ma through it which should be enough

:Sean
:
: The right thing would be to have a lower resistance field. Putting a resistor across the field helps but at some point you won't have enough voltage to magnatize the core.
:
: Here is another idea. Replace the field with a choke. Most chokes have much less resistance, around 300 ohms for 10 henries @ 70-90 ma.
:
: Now you still need to power the field. Connect your speaker field from B+ to ground with a resistor in series, 5K @ 10 watts should work.
:
: This will supply more voltage to your radio circuit and still power the field. Adjusting the resistor value controls voltage through the field.
:
:Norm
:
::Hello, also as expected volume got louder with more plate voltage, so If I go with adding parallel resistance, do I add enough to get to 155 volts(I think its 155 volts according to the schematic chart, its so small in writing its hard to read.
::
:::Hello, yes the radio did sound less distorted, more clearer even at lower volumes. So what should I do? Keep the speaker and add resistance in parallel or just get another speaker?
:::
::::Sean
::::
:::: Voltage will be lower with a load. You could try another 80 or add a 10 mfd @ 450 volt from pin #1 of your 80 to chassis. Think you did both of these already.
::::
:::: Looks like your field is just too high in resistance. As you found a 3000 ohm field with 37 ma drops 110 volts.
::::
:::: A 1000 ohm field under the same load will drop 37 volts. This is 73 volt difference. This difference will be less because as voltage increases so does current.
::::
:::: Did the radio sound less distorted with a 2.5K resistor?
::::
::::Norm
:::::Hello, If the power supply can put out 305v with no load, then it has to be good since it has no resistors in line with the B+, I thought there were but looked at schematic...there are none........interesting question is how much ma should this powersupply be able to handle?...100ma?
:::::
:::::::Hello, I am thinking the power supply is not high enough for some reason or the speaker field coil is too high in resistance
:::::::
:::::::Hello, I put a 2.5 kohm on and voltage jumps up to 100v plate on 71a. Overall B+ drops from 187 to 180. I got the 305 volts b+ by dissconnecting the radio from the power supply
:::::::
::::::::Hi Sean
::::::::
:::::::: Notice the voltage chart for US Radio Model 80. Voltages are way higher than your radio.
::::::::
:::::::: For a test add a 1000-2000 ohm 10 watt resistor across your field. See if this helps?
::::::::
:::::::: Your overall current is low because voltage is also low. When voltage is higher tubes will draw more current.
::::::::
::::::::Norm
::::::::
::::::::
:::::::::Hello, I just measured speaker field coil ma.........37ma.....I would think it should be at least 60ma....all the tube plate ma added up. the tube chart for the 71a lists 180 and 80 volts plate voltage. could this radio only need 80 volts plate on 71a?
:::::::::
::::::::::Hello, I just thought I would try a 10 uf cap to see if voltage rose any..didnt do anything except get rid of what little hum it had. The radio seems to be VERY close to a us radio model 80. The schematic even shows the terminals my power supply has. voltages match too. The power supply shows resistors in it, could they have drifted in value only showing up under load?
::::::::::
:::::::::::hello, the 305 volts is with no load, with load b+ drops to 187 at the power supply. I would assume all voltages are measured from pin one of the 71a. I just measured from plate to chassis ground and it is 82 volts
:::::::::::
::::::::::::Sean
::::::::::::
:::::::::::: Not a bad power transformer. A bad power transformer would be smoking..
::::::::::::
:::::::::::: Since I don't know the circuit pin numbers don't mean much. You seem to have good voltages. Voltage from pin 1 of the 80 to chassis will be DC.
::::::::::::
:::::::::::: If your speaker field drops 110 volts and you have 305 in the radio where does the rest go? That leaves 195 volts, plenty for the 71A circuit.
::::::::::::
::::::::::::Norm
::::::::::::
::::::::::::
:::::::::::::Hello I just switched the meter to a/c and it reads 118 volts at pin 1 of the 80 to pin 10 of terminals......bad cap maybe?
:::::::::::::
::::::::::::::Hello, no load voltage is 305 on pin 9 to pin 10. pin 1 of 80 to pin 10 of terminals is 229 volts. All of the previous readings were with the hi lo switch in the low position. So the 80 measurement in the lo position would be 208 volts...I HOPE THIS IS NOT ANOTHER BAD TRANS..SINCE THIS THING IS HUGE
::::::::::::::
:::::::::::::::Sean
:::::::::::::::
::::::::::::::: Plate voltage on your 71A's is too low. This will cause distortion with high volume. Why is your voltage so low?
:::::::::::::::
::::::::::::::: What voltage do you have on pin #1 of the 80? This will be highest in your radio. The highest you mentioned is 187 volts. Since 110 volts is dropped across the field this would leave 77 volts, not enough.
:::::::::::::::
::::::::::::::: Voltage will the same on both 71A's even if they aren't matched. For voltage measurement these tubes are tied together. If you were to remove one and measure both tubes pins they would still seem matched, even though one tube was pulled.
:::::::::::::::
:::::::::::::::Norm
:::::::::::::::
::::::::::::::::Hello measures grid to filament...its 13.74..so these tubes are good then?...they seem to be almost exact in voltage measurements so is that how they would be called a matched pair...I was wondering why tubes have to be matched
::::::::::::::::
:::::::::::::::::Hello, forgot to measure plate to filament.....74.6volts each
:::::::::::::::::
::::::::::::::::::Hello I just swapped the 80 tube just to see....no change
::::::::::::::::::
:::::::::::::::::::
:::::::::::::::::::Hello just measured speaker field coil voltage...its 110 volts.
::::::::::::::::::::Hello, I tested 71a tube voltages. from pin 1 to pin 2 is 75 volts. from pin 1 to pin 3 is -13.95v.....b+ seems to be low? Power supply pin 10 to 9 is 187v and pin 10 to pin 8 is 76v and pin 10 to pin 7 is 18v

6/2/2003 7:23:05 PMNorm Leal

A choke should be larger than that. Maybe 2" across? If you have an output transformer use it for test. It will act as a choke but not as efficient and may over heat in time.

Be sure the 4.7 K has a 10 watt rating. Anything smaller will overheat. Even 10 watts will be hot but within it's rating.

This idea will work well without buying another speaker.

Norm

:Hello, I might have a 10 henry choke, but am not sure how to check it. About how big should a 10 henry choke be? I found one in the TV. Its a little over an inch square(dont know if that helps So if I put a 4.7k resistor in series with the field coil then I would draw about 25 ma through it which should be enough
:
::Sean
::
:: The right thing would be to have a lower resistance field. Putting a resistor across the field helps but at some point you won't have enough voltage to magnatize the core.
::
:: Here is another idea. Replace the field with a choke. Most chokes have much less resistance, around 300 ohms for 10 henries @ 70-90 ma.
::
:: Now you still need to power the field. Connect your speaker field from B+ to ground with a resistor in series, 5K @ 10 watts should work.
::
:: This will supply more voltage to your radio circuit and still power the field. Adjusting the resistor value controls voltage through the field.
::
::Norm
::
:::Hello, also as expected volume got louder with more plate voltage, so If I go with adding parallel resistance, do I add enough to get to 155 volts(I think its 155 volts according to the schematic chart, its so small in writing its hard to read.
:::
::::Hello, yes the radio did sound less distorted, more clearer even at lower volumes. So what should I do? Keep the speaker and add resistance in parallel or just get another speaker?
::::
:::::Sean
:::::
::::: Voltage will be lower with a load. You could try another 80 or add a 10 mfd @ 450 volt from pin #1 of your 80 to chassis. Think you did both of these already.
:::::
::::: Looks like your field is just too high in resistance. As you found a 3000 ohm field with 37 ma drops 110 volts.
:::::
::::: A 1000 ohm field under the same load will drop 37 volts. This is 73 volt difference. This difference will be less because as voltage increases so does current.
:::::
::::: Did the radio sound less distorted with a 2.5K resistor?
:::::
:::::Norm
::::::Hello, If the power supply can put out 305v with no load, then it has to be good since it has no resistors in line with the B+, I thought there were but looked at schematic...there are none........interesting question is how much ma should this powersupply be able to handle?...100ma?
::::::
::::::::Hello, I am thinking the power supply is not high enough for some reason or the speaker field coil is too high in resistance
::::::::
::::::::Hello, I put a 2.5 kohm on and voltage jumps up to 100v plate on 71a. Overall B+ drops from 187 to 180. I got the 305 volts b+ by dissconnecting the radio from the power supply
::::::::
:::::::::Hi Sean
:::::::::
::::::::: Notice the voltage chart for US Radio Model 80. Voltages are way higher than your radio.
:::::::::
::::::::: For a test add a 1000-2000 ohm 10 watt resistor across your field. See if this helps?
:::::::::
::::::::: Your overall current is low because voltage is also low. When voltage is higher tubes will draw more current.
:::::::::
:::::::::Norm
:::::::::
:::::::::
::::::::::Hello, I just measured speaker field coil ma.........37ma.....I would think it should be at least 60ma....all the tube plate ma added up. the tube chart for the 71a lists 180 and 80 volts plate voltage. could this radio only need 80 volts plate on 71a?
::::::::::
:::::::::::Hello, I just thought I would try a 10 uf cap to see if voltage rose any..didnt do anything except get rid of what little hum it had. The radio seems to be VERY close to a us radio model 80. The schematic even shows the terminals my power supply has. voltages match too. The power supply shows resistors in it, could they have drifted in value only showing up under load?
:::::::::::
::::::::::::hello, the 305 volts is with no load, with load b+ drops to 187 at the power supply. I would assume all voltages are measured from pin one of the 71a. I just measured from plate to chassis ground and it is 82 volts
::::::::::::
:::::::::::::Sean
:::::::::::::
::::::::::::: Not a bad power transformer. A bad power transformer would be smoking..
:::::::::::::
::::::::::::: Since I don't know the circuit pin numbers don't mean much. You seem to have good voltages. Voltage from pin 1 of the 80 to chassis will be DC.
:::::::::::::
::::::::::::: If your speaker field drops 110 volts and you have 305 in the radio where does the rest go? That leaves 195 volts, plenty for the 71A circuit.
:::::::::::::
:::::::::::::Norm
:::::::::::::
:::::::::::::
::::::::::::::Hello I just switched the meter to a/c and it reads 118 volts at pin 1 of the 80 to pin 10 of terminals......bad cap maybe?
::::::::::::::
:::::::::::::::Hello, no load voltage is 305 on pin 9 to pin 10. pin 1 of 80 to pin 10 of terminals is 229 volts. All of the previous readings were with the hi lo switch in the low position. So the 80 measurement in the lo position would be 208 volts...I HOPE THIS IS NOT ANOTHER BAD TRANS..SINCE THIS THING IS HUGE
:::::::::::::::
::::::::::::::::Sean
::::::::::::::::
:::::::::::::::: Plate voltage on your 71A's is too low. This will cause distortion with high volume. Why is your voltage so low?
::::::::::::::::
:::::::::::::::: What voltage do you have on pin #1 of the 80? This will be highest in your radio. The highest you mentioned is 187 volts. Since 110 volts is dropped across the field this would leave 77 volts, not enough.
::::::::::::::::
:::::::::::::::: Voltage will the same on both 71A's even if they aren't matched. For voltage measurement these tubes are tied together. If you were to remove one and measure both tubes pins they would still seem matched, even though one tube was pulled.
::::::::::::::::
::::::::::::::::Norm
::::::::::::::::
:::::::::::::::::Hello measures grid to filament...its 13.74..so these tubes are good then?...they seem to be almost exact in voltage measurements so is that how they would be called a matched pair...I was wondering why tubes have to be matched
:::::::::::::::::
::::::::::::::::::Hello, forgot to measure plate to filament.....74.6volts each
::::::::::::::::::
:::::::::::::::::::Hello I just swapped the 80 tube just to see....no change
:::::::::::::::::::
::::::::::::::::::::
::::::::::::::::::::Hello just measured speaker field coil voltage...its 110 volts.
:::::::::::::::::::::Hello, I tested 71a tube voltages. from pin 1 to pin 2 is 75 volts. from pin 1 to pin 3 is -13.95v.....b+ seems to be low? Power supply pin 10 to 9 is 187v and pin 10 to pin 8 is 76v and pin 10 to pin 7 is 18v

6/2/2003 7:36:16 PMsean

Hello, I think there are two big transformers in the tv, but dont know if they are chokes or not. I see what you mean. I checked out AES and they sell them for about 20 bucks and fall within the 2 inch range...so i dont feel like shelling out another 25 bucks for a choke. I have a 4.7k 10watt that will work....its coming up with the choke that might be a problem....I did take one of the big ones out of the tv and it measures 14.7 ohms with the meter...will this work?

:A choke should be larger than that. Maybe 2" across? If you have an output transformer use it for test. It will act as a choke but not as efficient and may over heat in time.
:
:Be sure the 4.7 K has a 10 watt rating. Anything smaller will overheat. Even 10 watts will be hot but within it's rating.
:
:This idea will work well without buying another speaker.
:
:Norm
:
::Hello, I might have a 10 henry choke, but am not sure how to check it. About how big should a 10 henry choke be? I found one in the TV. Its a little over an inch square(dont know if that helps So if I put a 4.7k resistor in series with the field coil then I would draw about 25 ma through it which should be enough
::
:::Sean
:::
::: The right thing would be to have a lower resistance field. Putting a resistor across the field helps but at some point you won't have enough voltage to magnatize the core.
:::
::: Here is another idea. Replace the field with a choke. Most chokes have much less resistance, around 300 ohms for 10 henries @ 70-90 ma.
:::
::: Now you still need to power the field. Connect your speaker field from B+ to ground with a resistor in series, 5K @ 10 watts should work.
:::
::: This will supply more voltage to your radio circuit and still power the field. Adjusting the resistor value controls voltage through the field.
:::
:::Norm
:::
::::Hello, also as expected volume got louder with more plate voltage, so If I go with adding parallel resistance, do I add enough to get to 155 volts(I think its 155 volts according to the schematic chart, its so small in writing its hard to read.
::::
:::::Hello, yes the radio did sound less distorted, more clearer even at lower volumes. So what should I do? Keep the speaker and add resistance in parallel or just get another speaker?
:::::
::::::Sean
::::::
:::::: Voltage will be lower with a load. You could try another 80 or add a 10 mfd @ 450 volt from pin #1 of your 80 to chassis. Think you did both of these already.
::::::
:::::: Looks like your field is just too high in resistance. As you found a 3000 ohm field with 37 ma drops 110 volts.
::::::
:::::: A 1000 ohm field under the same load will drop 37 volts. This is 73 volt difference. This difference will be less because as voltage increases so does current.
::::::
:::::: Did the radio sound less distorted with a 2.5K resistor?
::::::
::::::Norm
:::::::Hello, If the power supply can put out 305v with no load, then it has to be good since it has no resistors in line with the B+, I thought there were but looked at schematic...there are none........interesting question is how much ma should this powersupply be able to handle?...100ma?
:::::::
:::::::::Hello, I am thinking the power supply is not high enough for some reason or the speaker field coil is too high in resistance
:::::::::
:::::::::Hello, I put a 2.5 kohm on and voltage jumps up to 100v plate on 71a. Overall B+ drops from 187 to 180. I got the 305 volts b+ by dissconnecting the radio from the power supply
:::::::::
::::::::::Hi Sean
::::::::::
:::::::::: Notice the voltage chart for US Radio Model 80. Voltages are way higher than your radio.
::::::::::
:::::::::: For a test add a 1000-2000 ohm 10 watt resistor across your field. See if this helps?
::::::::::
:::::::::: Your overall current is low because voltage is also low. When voltage is higher tubes will draw more current.
::::::::::
::::::::::Norm
::::::::::
::::::::::
:::::::::::Hello, I just measured speaker field coil ma.........37ma.....I would think it should be at least 60ma....all the tube plate ma added up. the tube chart for the 71a lists 180 and 80 volts plate voltage. could this radio only need 80 volts plate on 71a?
:::::::::::
::::::::::::Hello, I just thought I would try a 10 uf cap to see if voltage rose any..didnt do anything except get rid of what little hum it had. The radio seems to be VERY close to a us radio model 80. The schematic even shows the terminals my power supply has. voltages match too. The power supply shows resistors in it, could they have drifted in value only showing up under load?
::::::::::::
:::::::::::::hello, the 305 volts is with no load, with load b+ drops to 187 at the power supply. I would assume all voltages are measured from pin one of the 71a. I just measured from plate to chassis ground and it is 82 volts
:::::::::::::
::::::::::::::Sean
::::::::::::::
:::::::::::::: Not a bad power transformer. A bad power transformer would be smoking..
::::::::::::::
:::::::::::::: Since I don't know the circuit pin numbers don't mean much. You seem to have good voltages. Voltage from pin 1 of the 80 to chassis will be DC.
::::::::::::::
:::::::::::::: If your speaker field drops 110 volts and you have 305 in the radio where does the rest go? That leaves 195 volts, plenty for the 71A circuit.
::::::::::::::
::::::::::::::Norm
::::::::::::::
::::::::::::::
:::::::::::::::Hello I just switched the meter to a/c and it reads 118 volts at pin 1 of the 80 to pin 10 of terminals......bad cap maybe?
:::::::::::::::
::::::::::::::::Hello, no load voltage is 305 on pin 9 to pin 10. pin 1 of 80 to pin 10 of terminals is 229 volts. All of the previous readings were with the hi lo switch in the low position. So the 80 measurement in the lo position would be 208 volts...I HOPE THIS IS NOT ANOTHER BAD TRANS..SINCE THIS THING IS HUGE
::::::::::::::::
:::::::::::::::::Sean
:::::::::::::::::
::::::::::::::::: Plate voltage on your 71A's is too low. This will cause distortion with high volume. Why is your voltage so low?
:::::::::::::::::
::::::::::::::::: What voltage do you have on pin #1 of the 80? This will be highest in your radio. The highest you mentioned is 187 volts. Since 110 volts is dropped across the field this would leave 77 volts, not enough.
:::::::::::::::::
::::::::::::::::: Voltage will the same on both 71A's even if they aren't matched. For voltage measurement these tubes are tied together. If you were to remove one and measure both tubes pins they would still seem matched, even though one tube was pulled.
:::::::::::::::::
:::::::::::::::::Norm
:::::::::::::::::
::::::::::::::::::Hello measures grid to filament...its 13.74..so these tubes are good then?...they seem to be almost exact in voltage measurements so is that how they would be called a matched pair...I was wondering why tubes have to be matched
::::::::::::::::::
:::::::::::::::::::Hello, forgot to measure plate to filament.....74.6volts each
:::::::::::::::::::
::::::::::::::::::::Hello I just swapped the 80 tube just to see....no change
::::::::::::::::::::
:::::::::::::::::::::
:::::::::::::::::::::Hello just measured speaker field coil voltage...its 110 volts.
::::::::::::::::::::::Hello, I tested 71a tube voltages. from pin 1 to pin 2 is 75 volts. from pin 1 to pin 3 is -13.95v.....b+ seems to be low? Power supply pin 10 to 9 is 187v and pin 10 to pin 8 is 76v and pin 10 to pin 7 is 18v

6/2/2003 7:50:52 PMsean

Hello, since there is only about 187 volts on the power supply loaded then I wouldn't need much resistance in the b+ line. So would this tv choke work in conjunction with the field coil in series with a 4.7k to ground.

:Hello, I think there are two big transformers in the tv, but dont know if they are chokes or not. I see what you mean. I checked out AES and they sell them for about 20 bucks and fall within the 2 inch range...so i dont feel like shelling out another 25 bucks for a choke. I have a 4.7k 10watt that will work....its coming up with the choke that might be a problem....I did take one of the big ones out of the tv and it measures 14.7 ohms with the meter...will this work?
:
::A choke should be larger than that. Maybe 2" across? If you have an output transformer use it for test. It will act as a choke but not as efficient and may over heat in time.
::
::Be sure the 4.7 K has a 10 watt rating. Anything smaller will overheat. Even 10 watts will be hot but within it's rating.
::
::This idea will work well without buying another speaker.
::
::Norm
::
:::Hello, I might have a 10 henry choke, but am not sure how to check it. About how big should a 10 henry choke be? I found one in the TV. Its a little over an inch square(dont know if that helps So if I put a 4.7k resistor in series with the field coil then I would draw about 25 ma through it which should be enough
:::
::::Sean
::::
:::: The right thing would be to have a lower resistance field. Putting a resistor across the field helps but at some point you won't have enough voltage to magnatize the core.
::::
:::: Here is another idea. Replace the field with a choke. Most chokes have much less resistance, around 300 ohms for 10 henries @ 70-90 ma.
::::
:::: Now you still need to power the field. Connect your speaker field from B+ to ground with a resistor in series, 5K @ 10 watts should work.
::::
:::: This will supply more voltage to your radio circuit and still power the field. Adjusting the resistor value controls voltage through the field.
::::
::::Norm
::::
:::::Hello, also as expected volume got louder with more plate voltage, so If I go with adding parallel resistance, do I add enough to get to 155 volts(I think its 155 volts according to the schematic chart, its so small in writing its hard to read.
:::::
::::::Hello, yes the radio did sound less distorted, more clearer even at lower volumes. So what should I do? Keep the speaker and add resistance in parallel or just get another speaker?
::::::
:::::::Sean
:::::::
::::::: Voltage will be lower with a load. You could try another 80 or add a 10 mfd @ 450 volt from pin #1 of your 80 to chassis. Think you did both of these already.
:::::::
::::::: Looks like your field is just too high in resistance. As you found a 3000 ohm field with 37 ma drops 110 volts.
:::::::
::::::: A 1000 ohm field under the same load will drop 37 volts. This is 73 volt difference. This difference will be less because as voltage increases so does current.
:::::::
::::::: Did the radio sound less distorted with a 2.5K resistor?
:::::::
:::::::Norm
::::::::Hello, If the power supply can put out 305v with no load, then it has to be good since it has no resistors in line with the B+, I thought there were but looked at schematic...there are none........interesting question is how much ma should this powersupply be able to handle?...100ma?
::::::::
::::::::::Hello, I am thinking the power supply is not high enough for some reason or the speaker field coil is too high in resistance
::::::::::
::::::::::Hello, I put a 2.5 kohm on and voltage jumps up to 100v plate on 71a. Overall B+ drops from 187 to 180. I got the 305 volts b+ by dissconnecting the radio from the power supply
::::::::::
:::::::::::Hi Sean
:::::::::::
::::::::::: Notice the voltage chart for US Radio Model 80. Voltages are way higher than your radio.
:::::::::::
::::::::::: For a test add a 1000-2000 ohm 10 watt resistor across your field. See if this helps?
:::::::::::
::::::::::: Your overall current is low because voltage is also low. When voltage is higher tubes will draw more current.
:::::::::::
:::::::::::Norm
:::::::::::
:::::::::::
::::::::::::Hello, I just measured speaker field coil ma.........37ma.....I would think it should be at least 60ma....all the tube plate ma added up. the tube chart for the 71a lists 180 and 80 volts plate voltage. could this radio only need 80 volts plate on 71a?
::::::::::::
:::::::::::::Hello, I just thought I would try a 10 uf cap to see if voltage rose any..didnt do anything except get rid of what little hum it had. The radio seems to be VERY close to a us radio model 80. The schematic even shows the terminals my power supply has. voltages match too. The power supply shows resistors in it, could they have drifted in value only showing up under load?
:::::::::::::
::::::::::::::hello, the 305 volts is with no load, with load b+ drops to 187 at the power supply. I would assume all voltages are measured from pin one of the 71a. I just measured from plate to chassis ground and it is 82 volts
::::::::::::::
:::::::::::::::Sean
:::::::::::::::
::::::::::::::: Not a bad power transformer. A bad power transformer would be smoking..
:::::::::::::::
::::::::::::::: Since I don't know the circuit pin numbers don't mean much. You seem to have good voltages. Voltage from pin 1 of the 80 to chassis will be DC.
:::::::::::::::
::::::::::::::: If your speaker field drops 110 volts and you have 305 in the radio where does the rest go? That leaves 195 volts, plenty for the 71A circuit.
:::::::::::::::
:::::::::::::::Norm
:::::::::::::::
:::::::::::::::
::::::::::::::::Hello I just switched the meter to a/c and it reads 118 volts at pin 1 of the 80 to pin 10 of terminals......bad cap maybe?
::::::::::::::::
:::::::::::::::::Hello, no load voltage is 305 on pin 9 to pin 10. pin 1 of 80 to pin 10 of terminals is 229 volts. All of the previous readings were with the hi lo switch in the low position. So the 80 measurement in the lo position would be 208 volts...I HOPE THIS IS NOT ANOTHER BAD TRANS..SINCE THIS THING IS HUGE
:::::::::::::::::
::::::::::::::::::Sean
::::::::::::::::::
:::::::::::::::::: Plate voltage on your 71A's is too low. This will cause distortion with high volume. Why is your voltage so low?
::::::::::::::::::
:::::::::::::::::: What voltage do you have on pin #1 of the 80? This will be highest in your radio. The highest you mentioned is 187 volts. Since 110 volts is dropped across the field this would leave 77 volts, not enough.
::::::::::::::::::
:::::::::::::::::: Voltage will the same on both 71A's even if they aren't matched. For voltage measurement these tubes are tied together. If you were to remove one and measure both tubes pins they would still seem matched, even though one tube was pulled.
::::::::::::::::::
::::::::::::::::::Norm
::::::::::::::::::
:::::::::::::::::::Hello measures grid to filament...its 13.74..so these tubes are good then?...they seem to be almost exact in voltage measurements so is that how they would be called a matched pair...I was wondering why tubes have to be matched
:::::::::::::::::::
::::::::::::::::::::Hello, forgot to measure plate to filament.....74.6volts each
::::::::::::::::::::
:::::::::::::::::::::Hello I just swapped the 80 tube just to see....no change
:::::::::::::::::::::
::::::::::::::::::::::
::::::::::::::::::::::Hello just measured speaker field coil voltage...its 110 volts.
:::::::::::::::::::::::Hello, I tested 71a tube voltages. from pin 1 to pin 2 is 75 volts. from pin 1 to pin 3 is -13.95v.....b+ seems to be low? Power supply pin 10 to 9 is 187v and pin 10 to pin 8 is 76v and pin 10 to pin 7 is 18v

6/2/2003 10:06:32 PMNorm Leal

Sean

Try what you have. If it doesn't have enough inductance there might be hum. Increasing filter cap size should remove that. No need to spend a lot of money on a choke. Something you already have will work.

Norm

:Hello, since there is only about 187 volts on the power supply loaded then I wouldn't need much resistance in the b+ line. So would this tv choke work in conjunction with the field coil in series with a 4.7k to ground.
:
::Hello, I think there are two big transformers in the tv, but dont know if they are chokes or not. I see what you mean. I checked out AES and they sell them for about 20 bucks and fall within the 2 inch range...so i dont feel like shelling out another 25 bucks for a choke. I have a 4.7k 10watt that will work....its coming up with the choke that might be a problem....I did take one of the big ones out of the tv and it measures 14.7 ohms with the meter...will this work?
::
:::A choke should be larger than that. Maybe 2" across? If you have an output transformer use it for test. It will act as a choke but not as efficient and may over heat in time.
:::
:::Be sure the 4.7 K has a 10 watt rating. Anything smaller will overheat. Even 10 watts will be hot but within it's rating.
:::
:::This idea will work well without buying another speaker.
:::
:::Norm
:::
::::Hello, I might have a 10 henry choke, but am not sure how to check it. About how big should a 10 henry choke be? I found one in the TV. Its a little over an inch square(dont know if that helps So if I put a 4.7k resistor in series with the field coil then I would draw about 25 ma through it which should be enough
::::
:::::Sean
:::::
::::: The right thing would be to have a lower resistance field. Putting a resistor across the field helps but at some point you won't have enough voltage to magnatize the core.
:::::
::::: Here is another idea. Replace the field with a choke. Most chokes have much less resistance, around 300 ohms for 10 henries @ 70-90 ma.
:::::
::::: Now you still need to power the field. Connect your speaker field from B+ to ground with a resistor in series, 5K @ 10 watts should work.
:::::
::::: This will supply more voltage to your radio circuit and still power the field. Adjusting the resistor value controls voltage through the field.
:::::
:::::Norm
:::::
::::::Hello, also as expected volume got louder with more plate voltage, so If I go with adding parallel resistance, do I add enough to get to 155 volts(I think its 155 volts according to the schematic chart, its so small in writing its hard to read.
::::::
:::::::Hello, yes the radio did sound less distorted, more clearer even at lower volumes. So what should I do? Keep the speaker and add resistance in parallel or just get another speaker?
:::::::
::::::::Sean
::::::::
:::::::: Voltage will be lower with a load. You could try another 80 or add a 10 mfd @ 450 volt from pin #1 of your 80 to chassis. Think you did both of these already.
::::::::
:::::::: Looks like your field is just too high in resistance. As you found a 3000 ohm field with 37 ma drops 110 volts.
::::::::
:::::::: A 1000 ohm field under the same load will drop 37 volts. This is 73 volt difference. This difference will be less because as voltage increases so does current.
::::::::
:::::::: Did the radio sound less distorted with a 2.5K resistor?
::::::::
::::::::Norm
:::::::::Hello, If the power supply can put out 305v with no load, then it has to be good since it has no resistors in line with the B+, I thought there were but looked at schematic...there are none........interesting question is how much ma should this powersupply be able to handle?...100ma?
:::::::::
:::::::::::Hello, I am thinking the power supply is not high enough for some reason or the speaker field coil is too high in resistance
:::::::::::
:::::::::::Hello, I put a 2.5 kohm on and voltage jumps up to 100v plate on 71a. Overall B+ drops from 187 to 180. I got the 305 volts b+ by dissconnecting the radio from the power supply
:::::::::::
::::::::::::Hi Sean
::::::::::::
:::::::::::: Notice the voltage chart for US Radio Model 80. Voltages are way higher than your radio.
::::::::::::
:::::::::::: For a test add a 1000-2000 ohm 10 watt resistor across your field. See if this helps?
::::::::::::
:::::::::::: Your overall current is low because voltage is also low. When voltage is higher tubes will draw more current.
::::::::::::
::::::::::::Norm
::::::::::::
::::::::::::
:::::::::::::Hello, I just measured speaker field coil ma.........37ma.....I would think it should be at least 60ma....all the tube plate ma added up. the tube chart for the 71a lists 180 and 80 volts plate voltage. could this radio only need 80 volts plate on 71a?
:::::::::::::
::::::::::::::Hello, I just thought I would try a 10 uf cap to see if voltage rose any..didnt do anything except get rid of what little hum it had. The radio seems to be VERY close to a us radio model 80. The schematic even shows the terminals my power supply has. voltages match too. The power supply shows resistors in it, could they have drifted in value only showing up under load?
::::::::::::::
:::::::::::::::hello, the 305 volts is with no load, with load b+ drops to 187 at the power supply. I would assume all voltages are measured from pin one of the 71a. I just measured from plate to chassis ground and it is 82 volts
:::::::::::::::
::::::::::::::::Sean
::::::::::::::::
:::::::::::::::: Not a bad power transformer. A bad power transformer would be smoking..
::::::::::::::::
:::::::::::::::: Since I don't know the circuit pin numbers don't mean much. You seem to have good voltages. Voltage from pin 1 of the 80 to chassis will be DC.
::::::::::::::::
:::::::::::::::: If your speaker field drops 110 volts and you have 305 in the radio where does the rest go? That leaves 195 volts, plenty for the 71A circuit.
::::::::::::::::
::::::::::::::::Norm
::::::::::::::::
::::::::::::::::
:::::::::::::::::Hello I just switched the meter to a/c and it reads 118 volts at pin 1 of the 80 to pin 10 of terminals......bad cap maybe?
:::::::::::::::::
::::::::::::::::::Hello, no load voltage is 305 on pin 9 to pin 10. pin 1 of 80 to pin 10 of terminals is 229 volts. All of the previous readings were with the hi lo switch in the low position. So the 80 measurement in the lo position would be 208 volts...I HOPE THIS IS NOT ANOTHER BAD TRANS..SINCE THIS THING IS HUGE
::::::::::::::::::
:::::::::::::::::::Sean
:::::::::::::::::::
::::::::::::::::::: Plate voltage on your 71A's is too low. This will cause distortion with high volume. Why is your voltage so low?
:::::::::::::::::::
::::::::::::::::::: What voltage do you have on pin #1 of the 80? This will be highest in your radio. The highest you mentioned is 187 volts. Since 110 volts is dropped across the field this would leave 77 volts, not enough.
:::::::::::::::::::
::::::::::::::::::: Voltage will the same on both 71A's even if they aren't matched. For voltage measurement these tubes are tied together. If you were to remove one and measure both tubes pins they would still seem matched, even though one tube was pulled.
:::::::::::::::::::
:::::::::::::::::::Norm
:::::::::::::::::::
::::::::::::::::::::Hello measures grid to filament...its 13.74..so these tubes are good then?...they seem to be almost exact in voltage measurements so is that how they would be called a matched pair...I was wondering why tubes have to be matched
::::::::::::::::::::
:::::::::::::::::::::Hello, forgot to measure plate to filament.....74.6volts each
:::::::::::::::::::::
::::::::::::::::::::::Hello I just swapped the 80 tube just to see....no change
::::::::::::::::::::::
:::::::::::::::::::::::
:::::::::::::::::::::::Hello just measured speaker field coil voltage...its 110 volts.
::::::::::::::::::::::::Hello, I tested 71a tube voltages. from pin 1 to pin 2 is 75 volts. from pin 1 to pin 3 is -13.95v.....b+ seems to be low? Power supply pin 10 to 9 is 187v and pin 10 to pin 8 is 76v and pin 10 to pin 7 is 18v

6/3/2003 1:02:30 AMsean

Hello, I have the radio working at 137 volts on the plate(power supply is now at 142v) ma. is at 47. I am wondering if I am loading the power supply down too much since it is at 142. The schematic shows 165 plate voltage..so how did they get this...something in the power supply is weak or there is too much load. I am using the big choke out of the tv and it seems to be fine. voltage drop is .649v across the choke. The radio gets louder without distortion..so I bet it would get louder if I could get to 165 volts at the plate.

:Sean
:
: Try what you have. If it doesn't have enough inductance there might be hum. Increasing filter cap size should remove that. No need to spend a lot of money on a choke. Something you already have will work.
:
:Norm
:
::Hello, since there is only about 187 volts on the power supply loaded then I wouldn't need much resistance in the b+ line. So would this tv choke work in conjunction with the field coil in series with a 4.7k to ground.
::
:::Hello, I think there are two big transformers in the tv, but dont know if they are chokes or not. I see what you mean. I checked out AES and they sell them for about 20 bucks and fall within the 2 inch range...so i dont feel like shelling out another 25 bucks for a choke. I have a 4.7k 10watt that will work....its coming up with the choke that might be a problem....I did take one of the big ones out of the tv and it measures 14.7 ohms with the meter...will this work?
:::
::::A choke should be larger than that. Maybe 2" across? If you have an output transformer use it for test. It will act as a choke but not as efficient and may over heat in time.
::::
::::Be sure the 4.7 K has a 10 watt rating. Anything smaller will overheat. Even 10 watts will be hot but within it's rating.
::::
::::This idea will work well without buying another speaker.
::::
::::Norm
::::
:::::Hello, I might have a 10 henry choke, but am not sure how to check it. About how big should a 10 henry choke be? I found one in the TV. Its a little over an inch square(dont know if that helps So if I put a 4.7k resistor in series with the field coil then I would draw about 25 ma through it which should be enough
:::::
::::::Sean
::::::
:::::: The right thing would be to have a lower resistance field. Putting a resistor across the field helps but at some point you won't have enough voltage to magnatize the core.
::::::
:::::: Here is another idea. Replace the field with a choke. Most chokes have much less resistance, around 300 ohms for 10 henries @ 70-90 ma.
::::::
:::::: Now you still need to power the field. Connect your speaker field from B+ to ground with a resistor in series, 5K @ 10 watts should work.
::::::
:::::: This will supply more voltage to your radio circuit and still power the field. Adjusting the resistor value controls voltage through the field.
::::::
::::::Norm
::::::
:::::::Hello, also as expected volume got louder with more plate voltage, so If I go with adding parallel resistance, do I add enough to get to 155 volts(I think its 155 volts according to the schematic chart, its so small in writing its hard to read.
:::::::
::::::::Hello, yes the radio did sound less distorted, more clearer even at lower volumes. So what should I do? Keep the speaker and add resistance in parallel or just get another speaker?
::::::::
:::::::::Sean
:::::::::
::::::::: Voltage will be lower with a load. You could try another 80 or add a 10 mfd @ 450 volt from pin #1 of your 80 to chassis. Think you did both of these already.
:::::::::
::::::::: Looks like your field is just too high in resistance. As you found a 3000 ohm field with 37 ma drops 110 volts.
:::::::::
::::::::: A 1000 ohm field under the same load will drop 37 volts. This is 73 volt difference. This difference will be less because as voltage increases so does current.
:::::::::
::::::::: Did the radio sound less distorted with a 2.5K resistor?
:::::::::
:::::::::Norm
::::::::::Hello, If the power supply can put out 305v with no load, then it has to be good since it has no resistors in line with the B+, I thought there were but looked at schematic...there are none........interesting question is how much ma should this powersupply be able to handle?...100ma?
::::::::::
::::::::::::Hello, I am thinking the power supply is not high enough for some reason or the speaker field coil is too high in resistance
::::::::::::
::::::::::::Hello, I put a 2.5 kohm on and voltage jumps up to 100v plate on 71a. Overall B+ drops from 187 to 180. I got the 305 volts b+ by dissconnecting the radio from the power supply
::::::::::::
:::::::::::::Hi Sean
:::::::::::::
::::::::::::: Notice the voltage chart for US Radio Model 80. Voltages are way higher than your radio.
:::::::::::::
::::::::::::: For a test add a 1000-2000 ohm 10 watt resistor across your field. See if this helps?
:::::::::::::
::::::::::::: Your overall current is low because voltage is also low. When voltage is higher tubes will draw more current.
:::::::::::::
:::::::::::::Norm
:::::::::::::
:::::::::::::
::::::::::::::Hello, I just measured speaker field coil ma.........37ma.....I would think it should be at least 60ma....all the tube plate ma added up. the tube chart for the 71a lists 180 and 80 volts plate voltage. could this radio only need 80 volts plate on 71a?
::::::::::::::
:::::::::::::::Hello, I just thought I would try a 10 uf cap to see if voltage rose any..didnt do anything except get rid of what little hum it had. The radio seems to be VERY close to a us radio model 80. The schematic even shows the terminals my power supply has. voltages match too. The power supply shows resistors in it, could they have drifted in value only showing up under load?
:::::::::::::::
::::::::::::::::hello, the 305 volts is with no load, with load b+ drops to 187 at the power supply. I would assume all voltages are measured from pin one of the 71a. I just measured from plate to chassis ground and it is 82 volts
::::::::::::::::
:::::::::::::::::Sean
:::::::::::::::::
::::::::::::::::: Not a bad power transformer. A bad power transformer would be smoking..
:::::::::::::::::
::::::::::::::::: Since I don't know the circuit pin numbers don't mean much. You seem to have good voltages. Voltage from pin 1 of the 80 to chassis will be DC.
:::::::::::::::::
::::::::::::::::: If your speaker field drops 110 volts and you have 305 in the radio where does the rest go? That leaves 195 volts, plenty for the 71A circuit.
:::::::::::::::::
:::::::::::::::::Norm
:::::::::::::::::
:::::::::::::::::
::::::::::::::::::Hello I just switched the meter to a/c and it reads 118 volts at pin 1 of the 80 to pin 10 of terminals......bad cap maybe?
::::::::::::::::::
:::::::::::::::::::Hello, no load voltage is 305 on pin 9 to pin 10. pin 1 of 80 to pin 10 of terminals is 229 volts. All of the previous readings were with the hi lo switch in the low position. So the 80 measurement in the lo position would be 208 volts...I HOPE THIS IS NOT ANOTHER BAD TRANS..SINCE THIS THING IS HUGE
:::::::::::::::::::
::::::::::::::::::::Sean
::::::::::::::::::::
:::::::::::::::::::: Plate voltage on your 71A's is too low. This will cause distortion with high volume. Why is your voltage so low?
::::::::::::::::::::
:::::::::::::::::::: What voltage do you have on pin #1 of the 80? This will be highest in your radio. The highest you mentioned is 187 volts. Since 110 volts is dropped across the field this would leave 77 volts, not enough.
::::::::::::::::::::
:::::::::::::::::::: Voltage will the same on both 71A's even if they aren't matched. For voltage measurement these tubes are tied together. If you were to remove one and measure both tubes pins they would still seem matched, even though one tube was pulled.
::::::::::::::::::::
::::::::::::::::::::Norm
::::::::::::::::::::
:::::::::::::::::::::Hello measures grid to filament...its 13.74..so these tubes are good then?...they seem to be almost exact in voltage measurements so is that how they would be called a matched pair...I was wondering why tubes have to be matched
:::::::::::::::::::::
::::::::::::::::::::::Hello, forgot to measure plate to filament.....74.6volts each
::::::::::::::::::::::
:::::::::::::::::::::::Hello I just swapped the 80 tube just to see....no change
:::::::::::::::::::::::
::::::::::::::::::::::::
::::::::::::::::::::::::Hello just measured speaker field coil voltage...its 110 volts.
:::::::::::::::::::::::::Hello, I tested 71a tube voltages. from pin 1 to pin 2 is 75 volts. from pin 1 to pin 3 is -13.95v.....b+ seems to be low? Power supply pin 10 to 9 is 187v and pin 10 to pin 8 is 76v and pin 10 to pin 7 is 18v

6/3/2003 1:05:38 AMsean

Hello, the choke doesnt seem to do anything since i have a 20uf cap in place

:Hello, I have the radio working at 137 volts on the plate(power supply is now at 142v) ma. is at 47. I am wondering if I am loading the power supply down too much since it is at 142. The schematic shows 165 plate voltage..so how did they get this...something in the power supply is weak or there is too much load. I am using the big choke out of the tv and it seems to be fine. voltage drop is .649v across the choke. The radio gets louder without distortion..so I bet it would get louder if I could get to 165 volts at the plate.
:
::Sean
::
:: Try what you have. If it doesn't have enough inductance there might be hum. Increasing filter cap size should remove that. No need to spend a lot of money on a choke. Something you already have will work.
::
::Norm
::
:::Hello, since there is only about 187 volts on the power supply loaded then I wouldn't need much resistance in the b+ line. So would this tv choke work in conjunction with the field coil in series with a 4.7k to ground.
:::
::::Hello, I think there are two big transformers in the tv, but dont know if they are chokes or not. I see what you mean. I checked out AES and they sell them for about 20 bucks and fall within the 2 inch range...so i dont feel like shelling out another 25 bucks for a choke. I have a 4.7k 10watt that will work....its coming up with the choke that might be a problem....I did take one of the big ones out of the tv and it measures 14.7 ohms with the meter...will this work?
::::
:::::A choke should be larger than that. Maybe 2" across? If you have an output transformer use it for test. It will act as a choke but not as efficient and may over heat in time.
:::::
:::::Be sure the 4.7 K has a 10 watt rating. Anything smaller will overheat. Even 10 watts will be hot but within it's rating.
:::::
:::::This idea will work well without buying another speaker.
:::::
:::::Norm
:::::
::::::Hello, I might have a 10 henry choke, but am not sure how to check it. About how big should a 10 henry choke be? I found one in the TV. Its a little over an inch square(dont know if that helps So if I put a 4.7k resistor in series with the field coil then I would draw about 25 ma through it which should be enough
::::::
:::::::Sean
:::::::
::::::: The right thing would be to have a lower resistance field. Putting a resistor across the field helps but at some point you won't have enough voltage to magnatize the core.
:::::::
::::::: Here is another idea. Replace the field with a choke. Most chokes have much less resistance, around 300 ohms for 10 henries @ 70-90 ma.
:::::::
::::::: Now you still need to power the field. Connect your speaker field from B+ to ground with a resistor in series, 5K @ 10 watts should work.
:::::::
::::::: This will supply more voltage to your radio circuit and still power the field. Adjusting the resistor value controls voltage through the field.
:::::::
:::::::Norm
:::::::
::::::::Hello, also as expected volume got louder with more plate voltage, so If I go with adding parallel resistance, do I add enough to get to 155 volts(I think its 155 volts according to the schematic chart, its so small in writing its hard to read.
::::::::
:::::::::Hello, yes the radio did sound less distorted, more clearer even at lower volumes. So what should I do? Keep the speaker and add resistance in parallel or just get another speaker?
:::::::::
::::::::::Sean
::::::::::
:::::::::: Voltage will be lower with a load. You could try another 80 or add a 10 mfd @ 450 volt from pin #1 of your 80 to chassis. Think you did both of these already.
::::::::::
:::::::::: Looks like your field is just too high in resistance. As you found a 3000 ohm field with 37 ma drops 110 volts.
::::::::::
:::::::::: A 1000 ohm field under the same load will drop 37 volts. This is 73 volt difference. This difference will be less because as voltage increases so does current.
::::::::::
:::::::::: Did the radio sound less distorted with a 2.5K resistor?
::::::::::
::::::::::Norm
:::::::::::Hello, If the power supply can put out 305v with no load, then it has to be good since it has no resistors in line with the B+, I thought there were but looked at schematic...there are none........interesting question is how much ma should this powersupply be able to handle?...100ma?
:::::::::::
:::::::::::::Hello, I am thinking the power supply is not high enough for some reason or the speaker field coil is too high in resistance
:::::::::::::
:::::::::::::Hello, I put a 2.5 kohm on and voltage jumps up to 100v plate on 71a. Overall B+ drops from 187 to 180. I got the 305 volts b+ by dissconnecting the radio from the power supply
:::::::::::::
::::::::::::::Hi Sean
::::::::::::::
:::::::::::::: Notice the voltage chart for US Radio Model 80. Voltages are way higher than your radio.
::::::::::::::
:::::::::::::: For a test add a 1000-2000 ohm 10 watt resistor across your field. See if this helps?
::::::::::::::
:::::::::::::: Your overall current is low because voltage is also low. When voltage is higher tubes will draw more current.
::::::::::::::
::::::::::::::Norm
::::::::::::::
::::::::::::::
:::::::::::::::Hello, I just measured speaker field coil ma.........37ma.....I would think it should be at least 60ma....all the tube plate ma added up. the tube chart for the 71a lists 180 and 80 volts plate voltage. could this radio only need 80 volts plate on 71a?
:::::::::::::::
::::::::::::::::Hello, I just thought I would try a 10 uf cap to see if voltage rose any..didnt do anything except get rid of what little hum it had. The radio seems to be VERY close to a us radio model 80. The schematic even shows the terminals my power supply has. voltages match too. The power supply shows resistors in it, could they have drifted in value only showing up under load?
::::::::::::::::
:::::::::::::::::hello, the 305 volts is with no load, with load b+ drops to 187 at the power supply. I would assume all voltages are measured from pin one of the 71a. I just measured from plate to chassis ground and it is 82 volts
:::::::::::::::::
::::::::::::::::::Sean
::::::::::::::::::
:::::::::::::::::: Not a bad power transformer. A bad power transformer would be smoking..
::::::::::::::::::
:::::::::::::::::: Since I don't know the circuit pin numbers don't mean much. You seem to have good voltages. Voltage from pin 1 of the 80 to chassis will be DC.
::::::::::::::::::
:::::::::::::::::: If your speaker field drops 110 volts and you have 305 in the radio where does the rest go? That leaves 195 volts, plenty for the 71A circuit.
::::::::::::::::::
::::::::::::::::::Norm
::::::::::::::::::
::::::::::::::::::
:::::::::::::::::::Hello I just switched the meter to a/c and it reads 118 volts at pin 1 of the 80 to pin 10 of terminals......bad cap maybe?
:::::::::::::::::::
::::::::::::::::::::Hello, no load voltage is 305 on pin 9 to pin 10. pin 1 of 80 to pin 10 of terminals is 229 volts. All of the previous readings were with the hi lo switch in the low position. So the 80 measurement in the lo position would be 208 volts...I HOPE THIS IS NOT ANOTHER BAD TRANS..SINCE THIS THING IS HUGE
::::::::::::::::::::
:::::::::::::::::::::Sean
:::::::::::::::::::::
::::::::::::::::::::: Plate voltage on your 71A's is too low. This will cause distortion with high volume. Why is your voltage so low?
:::::::::::::::::::::
::::::::::::::::::::: What voltage do you have on pin #1 of the 80? This will be highest in your radio. The highest you mentioned is 187 volts. Since 110 volts is dropped across the field this would leave 77 volts, not enough.
:::::::::::::::::::::
::::::::::::::::::::: Voltage will the same on both 71A's even if they aren't matched. For voltage measurement these tubes are tied together. If you were to remove one and measure both tubes pins they would still seem matched, even though one tube was pulled.
:::::::::::::::::::::
:::::::::::::::::::::Norm
:::::::::::::::::::::
::::::::::::::::::::::Hello measures grid to filament...its 13.74..so these tubes are good then?...they seem to be almost exact in voltage measurements so is that how they would be called a matched pair...I was wondering why tubes have to be matched
::::::::::::::::::::::
:::::::::::::::::::::::Hello, forgot to measure plate to filament.....74.6volts each
:::::::::::::::::::::::
::::::::::::::::::::::::Hello I just swapped the 80 tube just to see....no change
::::::::::::::::::::::::
:::::::::::::::::::::::::
:::::::::::::::::::::::::Hello just measured speaker field coil voltage...its 110 volts.
::::::::::::::::::::::::::Hello, I tested 71a tube voltages. from pin 1 to pin 2 is 75 volts. from pin 1 to pin 3 is -13.95v.....b+ seems to be low? Power supply pin 10 to 9 is 187v and pin 10 to pin 8 is 76v and pin 10 to pin 7 is 18v

6/3/2003 9:16:21 AMNorm Leal

Be sure you have a good 80 tube. Also you need a good filter capacitor from pin #1 of your 80 to chassis. Remove any old filter caps. They could be leaky? This will give max voltage. Is your meter reading right?

A load of 47 ma isn't too much. Your radio will handle this without dropping voltage that far if it's the same as US Radio Model 80?

That choke doesn't have enough turns to be effective. It will allow hum but not hurt anything while you are testing.

Norm

:Hello, the choke doesnt seem to do anything since i have a 20uf cap in place
:
::Hello, I have the radio working at 137 volts on the plate(power supply is now at 142v) ma. is at 47. I am wondering if I am loading the power supply down too much since it is at 142. The schematic shows 165 plate voltage..so how did they get this...something in the power supply is weak or there is too much load. I am using the big choke out of the tv and it seems to be fine. voltage drop is .649v across the choke. The radio gets louder without distortion..so I bet it would get louder if I could get to 165 volts at the plate.
::
:::Sean
:::
::: Try what you have. If it doesn't have enough inductance there might be hum. Increasing filter cap size should remove that. No need to spend a lot of money on a choke. Something you already have will work.
:::
:::Norm
:::
::::Hello, since there is only about 187 volts on the power supply loaded then I wouldn't need much resistance in the b+ line. So would this tv choke work in conjunction with the field coil in series with a 4.7k to ground.
::::
:::::Hello, I think there are two big transformers in the tv, but dont know if they are chokes or not. I see what you mean. I checked out AES and they sell them for about 20 bucks and fall within the 2 inch range...so i dont feel like shelling out another 25 bucks for a choke. I have a 4.7k 10watt that will work....its coming up with the choke that might be a problem....I did take one of the big ones out of the tv and it measures 14.7 ohms with the meter...will this work?
:::::
::::::A choke should be larger than that. Maybe 2" across? If you have an output transformer use it for test. It will act as a choke but not as efficient and may over heat in time.
::::::
::::::Be sure the 4.7 K has a 10 watt rating. Anything smaller will overheat. Even 10 watts will be hot but within it's rating.
::::::
::::::This idea will work well without buying another speaker.
::::::
::::::Norm
::::::
:::::::Hello, I might have a 10 henry choke, but am not sure how to check it. About how big should a 10 henry choke be? I found one in the TV. Its a little over an inch square(dont know if that helps So if I put a 4.7k resistor in series with the field coil then I would draw about 25 ma through it which should be enough
:::::::
::::::::Sean
::::::::
:::::::: The right thing would be to have a lower resistance field. Putting a resistor across the field helps but at some point you won't have enough voltage to magnatize the core.
::::::::
:::::::: Here is another idea. Replace the field with a choke. Most chokes have much less resistance, around 300 ohms for 10 henries @ 70-90 ma.
::::::::
:::::::: Now you still need to power the field. Connect your speaker field from B+ to ground with a resistor in series, 5K @ 10 watts should work.
::::::::
:::::::: This will supply more voltage to your radio circuit and still power the field. Adjusting the resistor value controls voltage through the field.
::::::::
::::::::Norm
::::::::
:::::::::Hello, also as expected volume got louder with more plate voltage, so If I go with adding parallel resistance, do I add enough to get to 155 volts(I think its 155 volts according to the schematic chart, its so small in writing its hard to read.
:::::::::
::::::::::Hello, yes the radio did sound less distorted, more clearer even at lower volumes. So what should I do? Keep the speaker and add resistance in parallel or just get another speaker?
::::::::::
:::::::::::Sean
:::::::::::
::::::::::: Voltage will be lower with a load. You could try another 80 or add a 10 mfd @ 450 volt from pin #1 of your 80 to chassis. Think you did both of these already.
:::::::::::
::::::::::: Looks like your field is just too high in resistance. As you found a 3000 ohm field with 37 ma drops 110 volts.
:::::::::::
::::::::::: A 1000 ohm field under the same load will drop 37 volts. This is 73 volt difference. This difference will be less because as voltage increases so does current.
:::::::::::
::::::::::: Did the radio sound less distorted with a 2.5K resistor?
:::::::::::
:::::::::::Norm
::::::::::::Hello, If the power supply can put out 305v with no load, then it has to be good since it has no resistors in line with the B+, I thought there were but looked at schematic...there are none........interesting question is how much ma should this powersupply be able to handle?...100ma?
::::::::::::
::::::::::::::Hello, I am thinking the power supply is not high enough for some reason or the speaker field coil is too high in resistance
::::::::::::::
::::::::::::::Hello, I put a 2.5 kohm on and voltage jumps up to 100v plate on 71a. Overall B+ drops from 187 to 180. I got the 305 volts b+ by dissconnecting the radio from the power supply
::::::::::::::
:::::::::::::::Hi Sean
:::::::::::::::
::::::::::::::: Notice the voltage chart for US Radio Model 80. Voltages are way higher than your radio.
:::::::::::::::
::::::::::::::: For a test add a 1000-2000 ohm 10 watt resistor across your field. See if this helps?
:::::::::::::::
::::::::::::::: Your overall current is low because voltage is also low. When voltage is higher tubes will draw more current.
:::::::::::::::
:::::::::::::::Norm
:::::::::::::::
:::::::::::::::
::::::::::::::::Hello, I just measured speaker field coil ma.........37ma.....I would think it should be at least 60ma....all the tube plate ma added up. the tube chart for the 71a lists 180 and 80 volts plate voltage. could this radio only need 80 volts plate on 71a?
::::::::::::::::
:::::::::::::::::Hello, I just thought I would try a 10 uf cap to see if voltage rose any..didnt do anything except get rid of what little hum it had. The radio seems to be VERY close to a us radio model 80. The schematic even shows the terminals my power supply has. voltages match too. The power supply shows resistors in it, could they have drifted in value only showing up under load?
:::::::::::::::::
::::::::::::::::::hello, the 305 volts is with no load, with load b+ drops to 187 at the power supply. I would assume all voltages are measured from pin one of the 71a. I just measured from plate to chassis ground and it is 82 volts
::::::::::::::::::
:::::::::::::::::::Sean
:::::::::::::::::::
::::::::::::::::::: Not a bad power transformer. A bad power transformer would be smoking..
:::::::::::::::::::
::::::::::::::::::: Since I don't know the circuit pin numbers don't mean much. You seem to have good voltages. Voltage from pin 1 of the 80 to chassis will be DC.
:::::::::::::::::::
::::::::::::::::::: If your speaker field drops 110 volts and you have 305 in the radio where does the rest go? That leaves 195 volts, plenty for the 71A circuit.
:::::::::::::::::::
:::::::::::::::::::Norm
:::::::::::::::::::
:::::::::::::::::::
::::::::::::::::::::Hello I just switched the meter to a/c and it reads 118 volts at pin 1 of the 80 to pin 10 of terminals......bad cap maybe?
::::::::::::::::::::
:::::::::::::::::::::Hello, no load voltage is 305 on pin 9 to pin 10. pin 1 of 80 to pin 10 of terminals is 229 volts. All of the previous readings were with the hi lo switch in the low position. So the 80 measurement in the lo position would be 208 volts...I HOPE THIS IS NOT ANOTHER BAD TRANS..SINCE THIS THING IS HUGE
:::::::::::::::::::::
::::::::::::::::::::::Sean
::::::::::::::::::::::
:::::::::::::::::::::: Plate voltage on your 71A's is too low. This will cause distortion with high volume. Why is your voltage so low?
::::::::::::::::::::::
:::::::::::::::::::::: What voltage do you have on pin #1 of the 80? This will be highest in your radio. The highest you mentioned is 187 volts. Since 110 volts is dropped across the field this would leave 77 volts, not enough.
::::::::::::::::::::::
:::::::::::::::::::::: Voltage will the same on both 71A's even if they aren't matched. For voltage measurement these tubes are tied together. If you were to remove one and measure both tubes pins they would still seem matched, even though one tube was pulled.
::::::::::::::::::::::
::::::::::::::::::::::Norm
::::::::::::::::::::::
:::::::::::::::::::::::Hello measures grid to filament...its 13.74..so these tubes are good then?...they seem to be almost exact in voltage measurements so is that how they would be called a matched pair...I was wondering why tubes have to be matched
:::::::::::::::::::::::
::::::::::::::::::::::::Hello, forgot to measure plate to filament.....74.6volts each
::::::::::::::::::::::::
:::::::::::::::::::::::::Hello I just swapped the 80 tube just to see....no change
:::::::::::::::::::::::::
::::::::::::::::::::::::::
::::::::::::::::::::::::::Hello just measured speaker field coil voltage...its 110 volts.
:::::::::::::::::::::::::::Hello, I tested 71a tube voltages. from pin 1 to pin 2 is 75 volts. from pin 1 to pin 3 is -13.95v.....b+ seems to be low? Power supply pin 10 to 9 is 187v and pin 10 to pin 8 is 76v and pin 10 to pin 7 is 18v

6/3/2003 4:00:02 PMsean

Hello, I am trying to replace the caps to see if that will help my low B+ voltage, but this thing basically consists of 3 tall rectangular metal cases in line with resistive wire wound on very long circuit boards(1" by 10") on top of those cases, Then there is a metal bar containing the 10 terminals on top of that. Question is how hard is it to get at the caps to replace them? Also which metal case are they contained in? This thing really looks like it is a us radio model 80 power supply, but I am just wondering if its worth it to try and disassemble it to get at the caps

:Be sure you have a good 80 tube. Also you need a good filter capacitor from pin #1 of your 80 to chassis. Remove any old filter caps. They could be leaky? This will give max voltage. Is your meter reading right?
:
:A load of 47 ma isn't too much. Your radio will handle this without dropping voltage that far if it's the same as US Radio Model 80?
:
:That choke doesn't have enough turns to be effective. It will allow hum but not hurt anything while you are testing.
:
:Norm
:
::Hello, the choke doesnt seem to do anything since i have a 20uf cap in place
::
:::Hello, I have the radio working at 137 volts on the plate(power supply is now at 142v) ma. is at 47. I am wondering if I am loading the power supply down too much since it is at 142. The schematic shows 165 plate voltage..so how did they get this...something in the power supply is weak or there is too much load. I am using the big choke out of the tv and it seems to be fine. voltage drop is .649v across the choke. The radio gets louder without distortion..so I bet it would get louder if I could get to 165 volts at the plate.
:::
::::Sean
::::
:::: Try what you have. If it doesn't have enough inductance there might be hum. Increasing filter cap size should remove that. No need to spend a lot of money on a choke. Something you already have will work.
::::
::::Norm
::::
:::::Hello, since there is only about 187 volts on the power supply loaded then I wouldn't need much resistance in the b+ line. So would this tv choke work in conjunction with the field coil in series with a 4.7k to ground.
:::::
::::::Hello, I think there are two big transformers in the tv, but dont know if they are chokes or not. I see what you mean. I checked out AES and they sell them for about 20 bucks and fall within the 2 inch range...so i dont feel like shelling out another 25 bucks for a choke. I have a 4.7k 10watt that will work....its coming up with the choke that might be a problem....I did take one of the big ones out of the tv and it measures 14.7 ohms with the meter...will this work?
::::::
:::::::A choke should be larger than that. Maybe 2" across? If you have an output transformer use it for test. It will act as a choke but not as efficient and may over heat in time.
:::::::
:::::::Be sure the 4.7 K has a 10 watt rating. Anything smaller will overheat. Even 10 watts will be hot but within it's rating.
:::::::
:::::::This idea will work well without buying another speaker.
:::::::
:::::::Norm
:::::::
::::::::Hello, I might have a 10 henry choke, but am not sure how to check it. About how big should a 10 henry choke be? I found one in the TV. Its a little over an inch square(dont know if that helps So if I put a 4.7k resistor in series with the field coil then I would draw about 25 ma through it which should be enough
::::::::
:::::::::Sean
:::::::::
::::::::: The right thing would be to have a lower resistance field. Putting a resistor across the field helps but at some point you won't have enough voltage to magnatize the core.
:::::::::
::::::::: Here is another idea. Replace the field with a choke. Most chokes have much less resistance, around 300 ohms for 10 henries @ 70-90 ma.
:::::::::
::::::::: Now you still need to power the field. Connect your speaker field from B+ to ground with a resistor in series, 5K @ 10 watts should work.
:::::::::
::::::::: This will supply more voltage to your radio circuit and still power the field. Adjusting the resistor value controls voltage through the field.
:::::::::
:::::::::Norm
:::::::::
::::::::::Hello, also as expected volume got louder with more plate voltage, so If I go with adding parallel resistance, do I add enough to get to 155 volts(I think its 155 volts according to the schematic chart, its so small in writing its hard to read.
::::::::::
:::::::::::Hello, yes the radio did sound less distorted, more clearer even at lower volumes. So what should I do? Keep the speaker and add resistance in parallel or just get another speaker?
:::::::::::
::::::::::::Sean
::::::::::::
:::::::::::: Voltage will be lower with a load. You could try another 80 or add a 10 mfd @ 450 volt from pin #1 of your 80 to chassis. Think you did both of these already.
::::::::::::
:::::::::::: Looks like your field is just too high in resistance. As you found a 3000 ohm field with 37 ma drops 110 volts.
::::::::::::
:::::::::::: A 1000 ohm field under the same load will drop 37 volts. This is 73 volt difference. This difference will be less because as voltage increases so does current.
::::::::::::
:::::::::::: Did the radio sound less distorted with a 2.5K resistor?
::::::::::::
::::::::::::Norm
:::::::::::::Hello, If the power supply can put out 305v with no load, then it has to be good since it has no resistors in line with the B+, I thought there were but looked at schematic...there are none........interesting question is how much ma should this powersupply be able to handle?...100ma?
:::::::::::::
:::::::::::::::Hello, I am thinking the power supply is not high enough for some reason or the speaker field coil is too high in resistance
:::::::::::::::
:::::::::::::::Hello, I put a 2.5 kohm on and voltage jumps up to 100v plate on 71a. Overall B+ drops from 187 to 180. I got the 305 volts b+ by dissconnecting the radio from the power supply
:::::::::::::::
::::::::::::::::Hi Sean
::::::::::::::::
:::::::::::::::: Notice the voltage chart for US Radio Model 80. Voltages are way higher than your radio.
::::::::::::::::
:::::::::::::::: For a test add a 1000-2000 ohm 10 watt resistor across your field. See if this helps?
::::::::::::::::
:::::::::::::::: Your overall current is low because voltage is also low. When voltage is higher tubes will draw more current.
::::::::::::::::
::::::::::::::::Norm
::::::::::::::::
::::::::::::::::
:::::::::::::::::Hello, I just measured speaker field coil ma.........37ma.....I would think it should be at least 60ma....all the tube plate ma added up. the tube chart for the 71a lists 180 and 80 volts plate voltage. could this radio only need 80 volts plate on 71a?
:::::::::::::::::
::::::::::::::::::Hello, I just thought I would try a 10 uf cap to see if voltage rose any..didnt do anything except get rid of what little hum it had. The radio seems to be VERY close to a us radio model 80. The schematic even shows the terminals my power supply has. voltages match too. The power supply shows resistors in it, could they have drifted in value only showing up under load?
::::::::::::::::::
:::::::::::::::::::hello, the 305 volts is with no load, with load b+ drops to 187 at the power supply. I would assume all voltages are measured from pin one of the 71a. I just measured from plate to chassis ground and it is 82 volts
:::::::::::::::::::
::::::::::::::::::::Sean
::::::::::::::::::::
:::::::::::::::::::: Not a bad power transformer. A bad power transformer would be smoking..
::::::::::::::::::::
:::::::::::::::::::: Since I don't know the circuit pin numbers don't mean much. You seem to have good voltages. Voltage from pin 1 of the 80 to chassis will be DC.
::::::::::::::::::::
:::::::::::::::::::: If your speaker field drops 110 volts and you have 305 in the radio where does the rest go? That leaves 195 volts, plenty for the 71A circuit.
::::::::::::::::::::
::::::::::::::::::::Norm
::::::::::::::::::::
::::::::::::::::::::
:::::::::::::::::::::Hello I just switched the meter to a/c and it reads 118 volts at pin 1 of the 80 to pin 10 of terminals......bad cap maybe?
:::::::::::::::::::::
::::::::::::::::::::::Hello, no load voltage is 305 on pin 9 to pin 10. pin 1 of 80 to pin 10 of terminals is 229 volts. All of the previous readings were with the hi lo switch in the low position. So the 80 measurement in the lo position would be 208 volts...I HOPE THIS IS NOT ANOTHER BAD TRANS..SINCE THIS THING IS HUGE
::::::::::::::::::::::
:::::::::::::::::::::::Sean
:::::::::::::::::::::::
::::::::::::::::::::::: Plate voltage on your 71A's is too low. This will cause distortion with high volume. Why is your voltage so low?
:::::::::::::::::::::::
::::::::::::::::::::::: What voltage do you have on pin #1 of the 80? This will be highest in your radio. The highest you mentioned is 187 volts. Since 110 volts is dropped across the field this would leave 77 volts, not enough.
:::::::::::::::::::::::
::::::::::::::::::::::: Voltage will the same on both 71A's even if they aren't matched. For voltage measurement these tubes are tied together. If you were to remove one and measure both tubes pins they would still seem matched, even though one tube was pulled.
:::::::::::::::::::::::
:::::::::::::::::::::::Norm
:::::::::::::::::::::::
::::::::::::::::::::::::Hello measures grid to filament...its 13.74..so these tubes are good then?...they seem to be almost exact in voltage measurements so is that how they would be called a matched pair...I was wondering why tubes have to be matched
::::::::::::::::::::::::
:::::::::::::::::::::::::Hello, forgot to measure plate to filament.....74.6volts each
:::::::::::::::::::::::::
::::::::::::::::::::::::::Hello I just swapped the 80 tube just to see....no change
::::::::::::::::::::::::::
:::::::::::::::::::::::::::
:::::::::::::::::::::::::::Hello just measured speaker field coil voltage...its 110 volts.
::::::::::::::::::::::::::::Hello, I tested 71a tube voltages. from pin 1 to pin 2 is 75 volts. from pin 1 to pin 3 is -13.95v.....b+ seems to be low? Power supply pin 10 to 9 is 187v and pin 10 to pin 8 is 76v and pin 10 to pin 7 is 18v

6/3/2003 4:09:22 PMsean

Hello, I am trying to replace the caps to see if that will help my low B+ voltage, but this thing basically consists of 3 tall rectangular metal cases in line with resistive wire wound on very long circuit boards(1" by 10") on top of those cases, Then there is a metal bar containing the 10 terminals on top of that. Question is how hard is it to get at the caps to replace them? Also which metal case are they contained in? This thing really looks like it is a us radio model 80 power supply, but I am just wondering if its worth it to try and disassemble it to get at the caps........uuuuuhhhh ooooooh..I thought I would check to see if these 3 metal cases were filled with tar..............THEY ARE..........SO now I am reeaally open to suggestions here is it looks like a real pain to replace the caps. I am wondering if the caps and inductors can be bypassed easily. Pins 7 through 10 are on or electrically near the caps and inductors
:Be sure you have a good 80 tube. Also you need a good filter capacitor from pin #1 of your 80 to chassis. Remove any old filter caps. They could be leaky? This will give max voltage. Is your meter reading right?
:
:A load of 47 ma isn't too much. Your radio will handle this without dropping voltage that far if it's the same as US Radio Model 80?
:
:That choke doesn't have enough turns to be effective. It will allow hum but not hurt anything while you are testing.
:
:Norm
:
::Hello, the choke doesnt seem to do anything since i have a 20uf cap in place
::
:::Hello, I have the radio working at 137 volts on the plate(power supply is now at 142v) ma. is at 47. I am wondering if I am loading the power supply down too much since it is at 142. The schematic shows 165 plate voltage..so how did they get this...something in the power supply is weak or there is too much load. I am using the big choke out of the tv and it seems to be fine. voltage drop is .649v across the choke. The radio gets louder without distortion..so I bet it would get louder if I could get to 165 volts at the plate.
:::
::::Sean
::::
:::: Try what you have. If it doesn't have enough inductance there might be hum. Increasing filter cap size should remove that. No need to spend a lot of money on a choke. Something you already have will work.
::::
::::Norm
::::
:::::Hello, since there is only about 187 volts on the power supply loaded then I wouldn't need much resistance in the b+ line. So would this tv choke work in conjunction with the field coil in series with a 4.7k to ground.
:::::
::::::Hello, I think there are two big transformers in the tv, but dont know if they are chokes or not. I see what you mean. I checked out AES and they sell them for about 20 bucks and fall within the 2 inch range...so i dont feel like shelling out another 25 bucks for a choke. I have a 4.7k 10watt that will work....its coming up with the choke that might be a problem....I did take one of the big ones out of the tv and it measures 14.7 ohms with the meter...will this work?
::::::
:::::::A choke should be larger than that. Maybe 2" across? If you have an output transformer use it for test. It will act as a choke but not as efficient and may over heat in time.
:::::::
:::::::Be sure the 4.7 K has a 10 watt rating. Anything smaller will overheat. Even 10 watts will be hot but within it's rating.
:::::::
:::::::This idea will work well without buying another speaker.
:::::::
:::::::Norm
:::::::
::::::::Hello, I might have a 10 henry choke, but am not sure how to check it. About how big should a 10 henry choke be? I found one in the TV. Its a little over an inch square(dont know if that helps So if I put a 4.7k resistor in series with the field coil then I would draw about 25 ma through it which should be enough
::::::::
:::::::::Sean
:::::::::
::::::::: The right thing would be to have a lower resistance field. Putting a resistor across the field helps but at some point you won't have enough voltage to magnatize the core.
:::::::::
::::::::: Here is another idea. Replace the field with a choke. Most chokes have much less resistance, around 300 ohms for 10 henries @ 70-90 ma.
:::::::::
::::::::: Now you still need to power the field. Connect your speaker field from B+ to ground with a resistor in series, 5K @ 10 watts should work.
:::::::::
::::::::: This will supply more voltage to your radio circuit and still power the field. Adjusting the resistor value controls voltage through the field.
:::::::::
:::::::::Norm
:::::::::
::::::::::Hello, also as expected volume got louder with more plate voltage, so If I go with adding parallel resistance, do I add enough to get to 155 volts(I think its 155 volts according to the schematic chart, its so small in writing its hard to read.
::::::::::
:::::::::::Hello, yes the radio did sound less distorted, more clearer even at lower volumes. So what should I do? Keep the speaker and add resistance in parallel or just get another speaker?
:::::::::::
::::::::::::Sean
::::::::::::
:::::::::::: Voltage will be lower with a load. You could try another 80 or add a 10 mfd @ 450 volt from pin #1 of your 80 to chassis. Think you did both of these already.
::::::::::::
:::::::::::: Looks like your field is just too high in resistance. As you found a 3000 ohm field with 37 ma drops 110 volts.
::::::::::::
:::::::::::: A 1000 ohm field under the same load will drop 37 volts. This is 73 volt difference. This difference will be less because as voltage increases so does current.
::::::::::::
:::::::::::: Did the radio sound less distorted with a 2.5K resistor?
::::::::::::
::::::::::::Norm
:::::::::::::Hello, If the power supply can put out 305v with no load, then it has to be good since it has no resistors in line with the B+, I thought there were but looked at schematic...there are none........interesting question is how much ma should this powersupply be able to handle?...100ma?
:::::::::::::
:::::::::::::::Hello, I am thinking the power supply is not high enough for some reason or the speaker field coil is too high in resistance
:::::::::::::::
:::::::::::::::Hello, I put a 2.5 kohm on and voltage jumps up to 100v plate on 71a. Overall B+ drops from 187 to 180. I got the 305 volts b+ by dissconnecting the radio from the power supply
:::::::::::::::
::::::::::::::::Hi Sean
::::::::::::::::
:::::::::::::::: Notice the voltage chart for US Radio Model 80. Voltages are way higher than your radio.
::::::::::::::::
:::::::::::::::: For a test add a 1000-2000 ohm 10 watt resistor across your field. See if this helps?
::::::::::::::::
:::::::::::::::: Your overall current is low because voltage is also low. When voltage is higher tubes will draw more current.
::::::::::::::::
::::::::::::::::Norm
::::::::::::::::
::::::::::::::::
:::::::::::::::::Hello, I just measured speaker field coil ma.........37ma.....I would think it should be at least 60ma....all the tube plate ma added up. the tube chart for the 71a lists 180 and 80 volts plate voltage. could this radio only need 80 volts plate on 71a?
:::::::::::::::::
::::::::::::::::::Hello, I just thought I would try a 10 uf cap to see if voltage rose any..didnt do anything except get rid of what little hum it had. The radio seems to be VERY close to a us radio model 80. The schematic even shows the terminals my power supply has. voltages match too. The power supply shows resistors in it, could they have drifted in value only showing up under load?
::::::::::::::::::
:::::::::::::::::::hello, the 305 volts is with no load, with load b+ drops to 187 at the power supply. I would assume all voltages are measured from pin one of the 71a. I just measured from plate to chassis ground and it is 82 volts
:::::::::::::::::::
::::::::::::::::::::Sean
::::::::::::::::::::
:::::::::::::::::::: Not a bad power transformer. A bad power transformer would be smoking..
::::::::::::::::::::
:::::::::::::::::::: Since I don't know the circuit pin numbers don't mean much. You seem to have good voltages. Voltage from pin 1 of the 80 to chassis will be DC.
::::::::::::::::::::
:::::::::::::::::::: If your speaker field drops 110 volts and you have 305 in the radio where does the rest go? That leaves 195 volts, plenty for the 71A circuit.
::::::::::::::::::::
::::::::::::::::::::Norm
::::::::::::::::::::
::::::::::::::::::::
:::::::::::::::::::::Hello I just switched the meter to a/c and it reads 118 volts at pin 1 of the 80 to pin 10 of terminals......bad cap maybe?
:::::::::::::::::::::
::::::::::::::::::::::Hello, no load voltage is 305 on pin 9 to pin 10. pin 1 of 80 to pin 10 of terminals is 229 volts. All of the previous readings were with the hi lo switch in the low position. So the 80 measurement in the lo position would be 208 volts...I HOPE THIS IS NOT ANOTHER BAD TRANS..SINCE THIS THING IS HUGE
::::::::::::::::::::::
:::::::::::::::::::::::Sean
:::::::::::::::::::::::
::::::::::::::::::::::: Plate voltage on your 71A's is too low. This will cause distortion with high volume. Why is your voltage so low?
:::::::::::::::::::::::
::::::::::::::::::::::: What voltage do you have on pin #1 of the 80? This will be highest in your radio. The highest you mentioned is 187 volts. Since 110 volts is dropped across the field this would leave 77 volts, not enough.
:::::::::::::::::::::::
::::::::::::::::::::::: Voltage will the same on both 71A's even if they aren't matched. For voltage measurement these tubes are tied together. If you were to remove one and measure both tubes pins they would still seem matched, even though one tube was pulled.
:::::::::::::::::::::::
:::::::::::::::::::::::Norm
:::::::::::::::::::::::
::::::::::::::::::::::::Hello measures grid to filament...its 13.74..so these tubes are good then?...they seem to be almost exact in voltage measurements so is that how they would be called a matched pair...I was wondering why tubes have to be matched
::::::::::::::::::::::::
:::::::::::::::::::::::::Hello, forgot to measure plate to filament.....74.6volts each
:::::::::::::::::::::::::
::::::::::::::::::::::::::Hello I just swapped the 80 tube just to see....no change
::::::::::::::::::::::::::
:::::::::::::::::::::::::::
:::::::::::::::::::::::::::Hello just measured speaker field coil voltage...its 110 volts.
::::::::::::::::::::::::::::Hello, I tested 71a tube voltages. from pin 1 to pin 2 is 75 volts. from pin 1 to pin 3 is -13.95v.....b+ seems to be low? Power supply pin 10 to 9 is 187v and pin 10 to pin 8 is 76v and pin 10 to pin 7 is 18v

6/3/2003 7:16:33 PMsean

Hello, I measured the power supply metal cases just so you could have an idea of how big this thing is..from left to right is the first case 4 5\8 by 4 /8, 2nd case is 3/34 by 5, 3rd case is 4 1/4 by 5. All of these are sheet metal which what appears to be tar similiar to what they filled the philco bakelight caps with. I scraped it with my finger nail and it seems to be a little harder than tar so I dont know what it actually is. I am wondering if the components can be removed with a heat gun? Since I am guessing the caps have to be replaced by now due to their age. Gary at ptop said they are probably paper? Can paper caps by leaky too? I thought electrolytics were used in power supplys?

:Hello, I am trying to replace the caps to see if that will help my low B+ voltage, but this thing basically consists of 3 tall rectangular metal cases in line with resistive wire wound on very long circuit boards(1" by 10") on top of those cases, Then there is a metal bar containing the 10 terminals on top of that. Question is how hard is it to get at the caps to replace them? Also which metal case are they contained in? This thing really looks like it is a us radio model 80 power supply, but I am just wondering if its worth it to try and disassemble it to get at the caps........uuuuuhhhh ooooooh..I thought I would check to see if these 3 metal cases were filled with tar..............THEY ARE..........SO now I am reeaally open to suggestions here is it looks like a real pain to replace the caps. I am wondering if the caps and inductors can be bypassed easily. Pins 7 through 10 are on or electrically near the caps and inductors
::Be sure you have a good 80 tube. Also you need a good filter capacitor from pin #1 of your 80 to chassis. Remove any old filter caps. They could be leaky? This will give max voltage. Is your meter reading right?
::
::A load of 47 ma isn't too much. Your radio will handle this without dropping voltage that far if it's the same as US Radio Model 80?
::
::That choke doesn't have enough turns to be effective. It will allow hum but not hurt anything while you are testing.
::
::Norm
::
:::Hello, the choke doesnt seem to do anything since i have a 20uf cap in place
:::
::::Hello, I have the radio working at 137 volts on the plate(power supply is now at 142v) ma. is at 47. I am wondering if I am loading the power supply down too much since it is at 142. The schematic shows 165 plate voltage..so how did they get this...something in the power supply is weak or there is too much load. I am using the big choke out of the tv and it seems to be fine. voltage drop is .649v across the choke. The radio gets louder without distortion..so I bet it would get louder if I could get to 165 volts at the plate.
::::
:::::Sean
:::::
::::: Try what you have. If it doesn't have enough inductance there might be hum. Increasing filter cap size should remove that. No need to spend a lot of money on a choke. Something you already have will work.
:::::
:::::Norm
:::::
::::::Hello, since there is only about 187 volts on the power supply loaded then I wouldn't need much resistance in the b+ line. So would this tv choke work in conjunction with the field coil in series with a 4.7k to ground.
::::::
:::::::Hello, I think there are two big transformers in the tv, but dont know if they are chokes or not. I see what you mean. I checked out AES and they sell them for about 20 bucks and fall within the 2 inch range...so i dont feel like shelling out another 25 bucks for a choke. I have a 4.7k 10watt that will work....its coming up with the choke that might be a problem....I did take one of the big ones out of the tv and it measures 14.7 ohms with the meter...will this work?
:::::::
::::::::A choke should be larger than that. Maybe 2" across? If you have an output transformer use it for test. It will act as a choke but not as efficient and may over heat in time.
::::::::
::::::::Be sure the 4.7 K has a 10 watt rating. Anything smaller will overheat. Even 10 watts will be hot but within it's rating.
::::::::
::::::::This idea will work well without buying another speaker.
::::::::
::::::::Norm
::::::::
:::::::::Hello, I might have a 10 henry choke, but am not sure how to check it. About how big should a 10 henry choke be? I found one in the TV. Its a little over an inch square(dont know if that helps So if I put a 4.7k resistor in series with the field coil then I would draw about 25 ma through it which should be enough
:::::::::
::::::::::Sean
::::::::::
:::::::::: The right thing would be to have a lower resistance field. Putting a resistor across the field helps but at some point you won't have enough voltage to magnatize the core.
::::::::::
:::::::::: Here is another idea. Replace the field with a choke. Most chokes have much less resistance, around 300 ohms for 10 henries @ 70-90 ma.
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:::::::::: Now you still need to power the field. Connect your speaker field from B+ to ground with a resistor in series, 5K @ 10 watts should work.
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:::::::::: This will supply more voltage to your radio circuit and still power the field. Adjusting the resistor value controls voltage through the field.
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::::::::::Norm
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:::::::::::Hello, also as expected volume got louder with more plate voltage, so If I go with adding parallel resistance, do I add enough to get to 155 volts(I think its 155 volts according to the schematic chart, its so small in writing its hard to read.
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::::::::::::Hello, yes the radio did sound less distorted, more clearer even at lower volumes. So what should I do? Keep the speaker and add resistance in parallel or just get another speaker?
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:::::::::::::Sean
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::::::::::::: Voltage will be lower with a load. You could try another 80 or add a 10 mfd @ 450 volt from pin #1 of your 80 to chassis. Think you did both of these already.
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::::::::::::: Looks like your field is just too high in resistance. As you found a 3000 ohm field with 37 ma drops 110 volts.
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::::::::::::: A 1000 ohm field under the same load will drop 37 volts. This is 73 volt difference. This difference will be less because as voltage increases so does current.
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::::::::::::: Did the radio sound less distorted with a 2.5K resistor?
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:::::::::::::Norm
::::::::::::::Hello, If the power supply can put out 305v with no load, then it has to be good since it has no resistors in line with the B+, I thought there were but looked at schematic...there are none........interesting question is how much ma should this powersupply be able to handle?...100ma?
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::::::::::::::::Hello, I am thinking the power supply is not high enough for some reason or the speaker field coil is too high in resistance
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::::::::::::::::Hello, I put a 2.5 kohm on and voltage jumps up to 100v plate on 71a. Overall B+ drops from 187 to 180. I got the 305 volts b+ by dissconnecting the radio from the power supply
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:::::::::::::::::Hi Sean
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::::::::::::::::: Notice the voltage chart for US Radio Model 80. Voltages are way higher than your radio.
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::::::::::::::::: For a test add a 1000-2000 ohm 10 watt resistor across your field. See if this helps?
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::::::::::::::::: Your overall current is low because voltage is also low. When voltage is higher tubes will draw more current.
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:::::::::::::::::Norm
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:::::::::::::::::
::::::::::::::::::Hello, I just measured speaker field coil ma.........37ma.....I would think it should be at least 60ma....all the tube plate ma added up. the tube chart for the 71a lists 180 and 80 volts plate voltage. could this radio only need 80 volts plate on 71a?
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:::::::::::::::::::Hello, I just thought I would try a 10 uf cap to see if voltage rose any..didnt do anything except get rid of what little hum it had. The radio seems to be VERY close to a us radio model 80. The schematic even shows the terminals my power supply has. voltages match too. The power supply shows resistors in it, could they have drifted in value only showing up under load?
:::::::::::::::::::
::::::::::::::::::::hello, the 305 volts is with no load, with load b+ drops to 187 at the power supply. I would assume all voltages are measured from pin one of the 71a. I just measured from plate to chassis ground and it is 82 volts
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:::::::::::::::::::::Sean
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::::::::::::::::::::: Not a bad power transformer. A bad power transformer would be smoking..
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::::::::::::::::::::: Since I don't know the circuit pin numbers don't mean much. You seem to have good voltages. Voltage from pin 1 of the 80 to chassis will be DC.
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::::::::::::::::::::: If your speaker field drops 110 volts and you have 305 in the radio where does the rest go? That leaves 195 volts, plenty for the 71A circuit.
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:::::::::::::::::::::Norm
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::::::::::::::::::::::Hello I just switched the meter to a/c and it reads 118 volts at pin 1 of the 80 to pin 10 of terminals......bad cap maybe?
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:::::::::::::::::::::::Hello, no load voltage is 305 on pin 9 to pin 10. pin 1 of 80 to pin 10 of terminals is 229 volts. All of the previous readings were with the hi lo switch in the low position. So the 80 measurement in the lo position would be 208 volts...I HOPE THIS IS NOT ANOTHER BAD TRANS..SINCE THIS THING IS HUGE
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::::::::::::::::::::::::Sean
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:::::::::::::::::::::::: Plate voltage on your 71A's is too low. This will cause distortion with high volume. Why is your voltage so low?
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:::::::::::::::::::::::: What voltage do you have on pin #1 of the 80? This will be highest in your radio. The highest you mentioned is 187 volts. Since 110 volts is dropped across the field this would leave 77 volts, not enough.
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:::::::::::::::::::::::: Voltage will the same on both 71A's even if they aren't matched. For voltage measurement these tubes are tied together. If you were to remove one and measure both tubes pins they would still seem matched, even though one tube was pulled.
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::::::::::::::::::::::::Norm
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:::::::::::::::::::::::::Hello measures grid to filament...its 13.74..so these tubes are good then?...they seem to be almost exact in voltage measurements so is that how they would be called a matched pair...I was wondering why tubes have to be matched
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::::::::::::::::::::::::::Hello, forgot to measure plate to filament.....74.6volts each
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:::::::::::::::::::::::::::Hello I just swapped the 80 tube just to see....no change
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::::::::::::::::::::::::::::Hello just measured speaker field coil voltage...its 110 volts.
:::::::::::::::::::::::::::::Hello, I tested 71a tube voltages. from pin 1 to pin 2 is 75 volts. from pin 1 to pin 3 is -13.95v.....b+ seems to be low? Power supply pin 10 to 9 is 187v and pin 10 to pin 8 is 76v and pin 10 to pin 7 is 18v