Measure plate and screen voltages on tubes. B+ starts at pin #8 on your 35Z5. Would expect around 125 volts on pin #8.
Shouldn't be much wrong as you had the radio working.
http://www.nostalgiaair.org/PagesByModel/098/M0024098.pdf
Norm
:Hi guys, I'm gonna crazy with this radio. I dont know what more to do with it, I change all capacytors and tubes, rewired it following the schematic, tested the mica caps and tested or replaced the faulty resistors and all seems to be right. the only thing was that AES sent me a 12SA7GT instead of the 12SA7 metal shell one and those tubes have slightly difference in the pin connections. However the radio sound some music with a medium Hum but one day suddenly stops to play music and now theres only the normal buzz on this kind of radios.
:I make several tests, I use the signal tracer and test the grid and plate of the 12SK7 theres no sound also I connect the antenna directly to these points and no sound is heared at the speaker. I test the tube and it show no short.
:Milton.
:Hi Milton
:
: Measure plate and screen voltages on tubes. B+ starts at pin #8 on your 35Z5. Would expect around 125 volts on pin #8.
:
: Shouldn't be much wrong as you had the radio working.
:
:http://www.nostalgiaair.org/PagesByModel/098/M0024098.pdf
:
:Norm
:
::Hi guys, I'm gonna crazy with this radio. I dont know what more to do with it, I change all capacytors and tubes, rewired it following the schematic, tested the mica caps and tested or replaced the faulty resistors and all seems to be right. the only thing was that AES sent me a 12SA7GT instead of the 12SA7 metal shell one and those tubes have slightly difference in the pin connections. However the radio sound some music with a medium Hum but one day suddenly stops to play music and now theres only the normal buzz on this kind of radios.
::I make several tests, I use the signal tracer and test the grid and plate of the 12SK7 theres no sound also I connect the antenna directly to these points and no sound is heared at the speaker. I test the tube and it show no short.
::Milton.
Use negative side of your electrolytic filter caps for the black meter lead. Chassis is not B- in this radio.
Do you hear hum touching the center terminal on the volume control? If you do audio stages are ok.
Connecting an antenna to different points in a superhet, like your radio, won't bring in stations. This is a good test on TRF radios. Most of these are from 1920's & 1930's.
Norm
:THANKS NORM, YES I HAVE HIGH VOLTAGE ON B+. THE LINK YOU SENT ME IS FOR THE SCHEMATICS, I HAVE BOTH THE RIDERS AND THE SAMS PHOTOFACT. AS YOU SEE IN THIS ONE THE PIN #8 IS SUPPOSELY TO GAVE A READ OF 130K RESISTANCE, I CHECK THIS POINT AND IT ONLY MEASURES THE CAPACYTOR CHARGE IT BEGINS TO READ UP AND UP WHILE THE CAP TAKE HIS CHARGE AND THEN READS ZERO.
:DO THIS HAVE SOME CONNECTION WITH THE PROBLEM?
:MILTON.
:
::Hi Milton
::
:: Measure plate and screen voltages on tubes. B+ starts at pin #8 on your 35Z5. Would expect around 125 volts on pin #8.
::
:: Shouldn't be much wrong as you had the radio working.
::
::http://www.nostalgiaair.org/PagesByModel/098/M0024098.pdf
::
::Norm
::
:::Hi guys, I'm gonna crazy with this radio. I dont know what more to do with it, I change all capacytors and tubes, rewired it following the schematic, tested the mica caps and tested or replaced the faulty resistors and all seems to be right. the only thing was that AES sent me a 12SA7GT instead of the 12SA7 metal shell one and those tubes have slightly difference in the pin connections. However the radio sound some music with a medium Hum but one day suddenly stops to play music and now theres only the normal buzz on this kind of radios.
:::I make several tests, I use the signal tracer and test the grid and plate of the 12SK7 theres no sound also I connect the antenna directly to these points and no sound is heared at the speaker. I test the tube and it show no short.
:::Milton.
:Hi Milton
:
: Use negative side of your electrolytic filter caps for the black meter lead. Chassis is not B- in this radio.
:
: Do you hear hum touching the center terminal on the volume control? If you do audio stages are ok.
:
: Connecting an antenna to different points in a superhet, like your radio, won't bring in stations. This is a good test on TRF radios. Most of these are from 1920's & 1930's.
:
:Norm
:
::THANKS NORM, YES I HAVE HIGH VOLTAGE ON B+. THE LINK YOU SENT ME IS FOR THE SCHEMATICS, I HAVE BOTH THE RIDERS AND THE SAMS PHOTOFACT. AS YOU SEE IN THIS ONE THE PIN #8 IS SUPPOSELY TO GAVE A READ OF 130K RESISTANCE, I CHECK THIS POINT AND IT ONLY MEASURES THE CAPACYTOR CHARGE IT BEGINS TO READ UP AND UP WHILE THE CAP TAKE HIS CHARGE AND THEN READS ZERO.
::DO THIS HAVE SOME CONNECTION WITH THE PROBLEM?
::MILTON.
::
:::Hi Milton
:::
::: Measure plate and screen voltages on tubes. B+ starts at pin #8 on your 35Z5. Would expect around 125 volts on pin #8.
:::
::: Shouldn't be much wrong as you had the radio working.
:::
:::http://www.nostalgiaair.org/PagesByModel/098/M0024098.pdf
:::
:::Norm
Thomas
:MIlton, Check your voltage supply, make sure your main bleeder resistor is not open or off on the resistance, I had a simular experiance with no RF and that was my radio problem, my resistor was open not allowing the correct voltage to the front end of the radio.
:Elton
::OK,I MAKE SEVERAL TESTS ON THIS RADIO AND THIS IS WHAT I FOUND, THE EXACT VOLTAGE IN PIN #8 IS 120.VDC, BUT PLATES AND GRIDS OF RF AMPLIFIER 12SK7 READS AND 12SA7 CONVERTER BETWEEN 12 AND 13VDC WHEN THEY SHOULD HAVE 31VDC PLATE AND 70VDC GRID. THE FILAMENTS ARE 12.93 VAC.
::MILTON
::
:::Hi Milton
:::
::: Use negative side of your electrolytic filter caps for the black meter lead. Chassis is not B- in this radio.
:::
::: Do you hear hum touching the center terminal on the volume control? If you do audio stages are ok.
:::
::: Connecting an antenna to different points in a superhet, like your radio, won't bring in stations. This is a good test on TRF radios. Most of these are from 1920's & 1930's.
:::
:::Norm
:::
::::THANKS NORM, YES I HAVE HIGH VOLTAGE ON B+. THE LINK YOU SENT ME IS FOR THE SCHEMATICS, I HAVE BOTH THE RIDERS AND THE SAMS PHOTOFACT. AS YOU SEE IN THIS ONE THE PIN #8 IS SUPPOSELY TO GAVE A READ OF 130K RESISTANCE, I CHECK THIS POINT AND IT ONLY MEASURES THE CAPACYTOR CHARGE IT BEGINS TO READ UP AND UP WHILE THE CAP TAKE HIS CHARGE AND THEN READS ZERO.
::::DO THIS HAVE SOME CONNECTION WITH THE PROBLEM?
::::MILTON.
::::
:::::Hi Milton
:::::
::::: Measure plate and screen voltages on tubes. B+ starts at pin #8 on your 35Z5. Would expect around 125 volts on pin #8.
:::::
::::: Shouldn't be much wrong as you had the radio working.
:::::
:::::http://www.nostalgiaair.org/PagesByModel/098/M0024098.pdf
:::::
:::::Norm
:....Especially since you hear a hum, but get no signal--the output tube of most AC-DC sets takes its voltage right off of the rectifier, and so you'll hear a hum even if the main bleeder resistor is open or drifted high (you say you have some voltage on RF tubes and can get a hum by touching the volume control, so some voltage is getting through if you say this, but not enough). Also be sure that if you replaced electrolytics that you didn't insert any backwards. On rare occasion you can put an electrolytic in backwards and it'll work for a while, but it'll fail, which will short out the power supply to various degrees.
:
:Thomas
:
::MIlton, Check your voltage supply, make sure your main bleeder resistor is not open or off on the resistance, I had a simular experiance with no RF and that was my radio problem, my resistor was open not allowing the correct voltage to the front end of the radio.
::Elton
http://www.nostalgiaair.org/PagesByModel/098/M0024098.pdf
The resistor in your radio cannot properly be called a bleeder resistor because it is not connected as mentioned above. It is simply a power reducing/power filtering resistor. It is resistor #35, the 1500 ohm resistor that feeds B+ to the rest of the radio. It does not feed B+ to the plate of the output tube. This is connected through the output transformer directly to the rectifier (B+). Check the above resistor and all voltages after it. If you are having voltage trouble in the set, but have full voltage at the rectifier and the plate of the output tube (this will be slightly less than that at the rectifier), this resistor is likely at fault.
Thomas
:EXCUSE MY IGNORANCE BUT...WHAT IS THE BLEEDER RESISTOR IN THIS RADIO? OR HOW CAN I RECOGNIZE IT?
:MILTON
:
::....Especially since you hear a hum, but get no signal--the output tube of most AC-DC sets takes its voltage right off of the rectifier, and so you'll hear a hum even if the main bleeder resistor is open or drifted high (you say you have some voltage on RF tubes and can get a hum by touching the volume control, so some voltage is getting through if you say this, but not enough). Also be sure that if you replaced electrolytics that you didn't insert any backwards. On rare occasion you can put an electrolytic in backwards and it'll work for a while, but it'll fail, which will short out the power supply to various degrees.
::
::Thomas
::
:::MIlton, Check your voltage supply, make sure your main bleeder resistor is not open or off on the resistance, I had a simular experiance with no RF and that was my radio problem, my resistor was open not allowing the correct voltage to the front end of the radio.
:::Elton
:
:http://www.nostalgiaair.org/PagesByModel/098/M0024098.pdf
:
MILTON
Remember that in the schematic wires that cross without a dot are not connected. Wires that cross with a dot are connected.
Thomas
::"Bleeder" resistor is actually a term which we were using improperly for the item. A bleeder resistor is an item that goes from B+ to B-. It may have several taps for various voltages that are found at various points on the resistor, to be used at various points within the set (grid bias, plate voltage, etc.). It is called a bleeder because when the radio is shut off it bleeds all of the current away due to its being connected across the power supply. This aids in relieving charges that might otherwise remain in electrolytics--a secondary feature of the resistor, which eliminates shock hazard after the set has been unplugged.
::
::The resistor in your radio cannot properly be called a bleeder resistor because it is not connected as mentioned above. It is simply a power reducing/power filtering resistor. It is resistor #35, the 1500 ohm resistor that feeds B+ to the rest of the radio. It does not feed B+ to the plate of the output tube. This is connected through the output transformer directly to the rectifier (B+). Check the above resistor and all voltages after it. If you are having voltage trouble in the set, but have full voltage at the rectifier and the plate of the output tube (this will be slightly less than that at the rectifier), this resistor is likely at fault.
::
::Thomas
::
:THOMAS, I CHECK THE B+ AND IT IS 116 VDC BEFORE THE RESISTOR AND 15 VDC AFTER IT. THE #35 RESISTOR IS 1487 OHM RESISTANCE THE #45 RESISTOR OF 350K IS 355K.
:
:MILTON