I've recapped and replaced out of tolerence resistors, checked tubes and ensured all circuits have continuity. I can push a BC signal through with the SG turned up, but it is up high enough that it should bast me out of the basement.
The signal drops dramatically at the secondary of the first IF. Alignment improves but does not bring the signal up to normal. Voltages are normal throughout the radio.
Placing my oscilloscope probe on the IF leads increases the volume significantly but the secondary of the first IF remains much weaker than the primary.
I've eliminated tubes, caps, resistors, incorrect wiring, open coils, I've run out of options. Anyone have any ideas?
Thanks for any help.
Bud R
Might try a known-good 6SQ7, if you have one, but if not, don't buy one.
Try jumpering across the 2nd IF xfmr with a 200-pF cap, per this suggestion: http://antiqueradios.com/chrs/journal/transformers.html
Did you have this problem before recapping, etc?
Here is the schematic: http://www.nostalgiaair.org/PagesByModel/012/M0008012.pdf
Doug
:Hello,
:
:I've recapped and replaced out of tolerence resistors, checked tubes and ensured all circuits have continuity. I can push a BC signal through with the SG turned up, but it is up high enough that it should bast me out of the basement.
:
:The signal drops dramatically at the secondary of the first IF. Alignment improves but does not bring the signal up to normal. Voltages are normal throughout the radio.
:
:Placing my oscilloscope probe on the IF leads increases the volume significantly but the secondary of the first IF remains much weaker than the primary.
:
:I've eliminated tubes, caps, resistors, incorrect wiring, open coils, I've run out of options. Anyone have any ideas?
:
:Thanks for any help.
:
:Bud R
There is 15 ohms across the pri and 47K across the sec winding. I opened the can and replaced the 47k resistor which was reading 61k.
I've swapped the 6SA7, 6SK7 and 6SQ7, no changes.
I have tried jumping both IFs with a 200 pf cap, it increased output slightly when I jumped the 1st IF, it had no effect on the 2nd IF.
A friend of mine re-capped this set and brought it to me when it wouldn't work. I found an ungrounded filter cap, a couple of bad solder joints a lot of resistors that had drifted high, a bad rectifier tube (this set uses two) and a bad 6SQ7. After correcting all that, I'm left with this problem.
I haven't opened up the first IF, the only thing inside are some micas. Could one of them be the culprit?
Best,
Bud.
:Bud, what resistance do you measure across the pri and sec windings of the 2nd IF xfmr?
:
:Might try a known-good 6SQ7, if you have one, but if not, don't buy one.
:
:Try jumpering across the 2nd IF xfmr with a 200-pF cap, per this suggestion: http://antiqueradios.com/chrs/journal/transformers.html
:
:Did you have this problem before recapping, etc?
:
:Here is the schematic: http://www.nostalgiaair.org/PagesByModel/012/M0008012.pdf
:Doug
:
::Hello,
::
::I've recapped and replaced out of tolerence resistors, checked tubes and ensured all circuits have continuity. I can push a BC signal through with the SG turned up, but it is up high enough that it should bast me out of the basement.
::
::The signal drops dramatically at the secondary of the first IF. Alignment improves but does not bring the signal up to normal. Voltages are normal throughout the radio.
::
::Placing my oscilloscope probe on the IF leads increases the volume significantly but the secondary of the first IF remains much weaker than the primary.
::
::I've eliminated tubes, caps, resistors, incorrect wiring, open coils, I've run out of options. Anyone have any ideas?
::
::Thanks for any help.
::
::Bud R
Doug,
:
:There is 15 ohms across the pri and 47K across the sec winding. I opened the can and replaced the 47k resistor which was reading 61k.
:
:I've swapped the 6SA7, 6SK7 and 6SQ7, no changes.
:
:I have tried jumping both IFs with a 200 pf cap, it increased output slightly when I jumped the 1st IF, it had no effect on the 2nd IF.
:
:A friend of mine re-capped this set and brought it to me when it wouldn't work. I found an ungrounded filter cap, a couple of bad solder joints a lot of resistors that had drifted high, a bad rectifier tube (this set uses two) and a bad 6SQ7. After correcting all that, I'm left with this problem.
:
:I haven't opened up the first IF, the only thing inside are some micas. Could one of them be the culprit?
:
:Best,
:
:Bud.
:
:
:
::Bud, what resistance do you measure across the pri and sec windings of the 2nd IF xfmr?
::
::Might try a known-good 6SQ7, if you have one, but if not, don't buy one.
::
::Try jumpering across the 2nd IF xfmr with a 200-pF cap, per this suggestion: http://antiqueradios.com/chrs/journal/transformers.html
::
::Did you have this problem before recapping, etc?
::
::Here is the schematic: http://www.nostalgiaair.org/PagesByModel/012/M0008012.pdf
::Doug
::
:::Hello,
:::
:::I've recapped and replaced out of tolerence resistors, checked tubes and ensured all circuits have continuity. I can push a BC signal through with the SG turned up, but it is up high enough that it should bast me out of the basement.
:::
:::The signal drops dramatically at the secondary of the first IF. Alignment improves but does not bring the signal up to normal. Voltages are normal throughout the radio.
:::
:::Placing my oscilloscope probe on the IF leads increases the volume significantly but the secondary of the first IF remains much weaker than the primary.
:::
:::I've eliminated tubes, caps, resistors, incorrect wiring, open coils, I've run out of options. Anyone have any ideas?
:::
:::Thanks for any help.
:::
:::Bud R
47K is correct, there is a resistor inside the can that is in series with the secondary winding.
Bud
Bud:
:47k across the secondary sure sounds like an open to me.
:Lewis
:
:
:
:
:Doug,
::
::There is 15 ohms across the pri and 47K across the sec winding. I opened the can and replaced the 47k resistor which was reading 61k.
::
::I've swapped the 6SA7, 6SK7 and 6SQ7, no changes.
::
::I have tried jumping both IFs with a 200 pf cap, it increased output slightly when I jumped the 1st IF, it had no effect on the 2nd IF.
::
::A friend of mine re-capped this set and brought it to me when it wouldn't work. I found an ungrounded filter cap, a couple of bad solder joints a lot of resistors that had drifted high, a bad rectifier tube (this set uses two) and a bad 6SQ7. After correcting all that, I'm left with this problem.
::
::I haven't opened up the first IF, the only thing inside are some micas. Could one of them be the culprit?
::
::Best,
::
::Bud.
::
::
::
:::Bud, what resistance do you measure across the pri and sec windings of the 2nd IF xfmr?
:::
:::Might try a known-good 6SQ7, if you have one, but if not, don't buy one.
:::
:::Try jumpering across the 2nd IF xfmr with a 200-pF cap, per this suggestion: http://antiqueradios.com/chrs/journal/transformers.html
:::
:::Did you have this problem before recapping, etc?
:::
:::Here is the schematic: http://www.nostalgiaair.org/PagesByModel/012/M0008012.pdf
:::Doug
:::
::::Hello,
::::
::::I've recapped and replaced out of tolerence resistors, checked tubes and ensured all circuits have continuity. I can push a BC signal through with the SG turned up, but it is up high enough that it should bast me out of the basement.
::::
::::The signal drops dramatically at the secondary of the first IF. Alignment improves but does not bring the signal up to normal. Voltages are normal throughout the radio.
::::
::::Placing my oscilloscope probe on the IF leads increases the volume significantly but the secondary of the first IF remains much weaker than the primary.
::::
::::I've eliminated tubes, caps, resistors, incorrect wiring, open coils, I've run out of options. Anyone have any ideas?
::::
::::Thanks for any help.
::::
::::Bud R
: Lewis,
:
:47K is correct, there is a resistor inside the can that is in series with the secondary winding.
:
:Bud
:
:
:Bud:
::47k across the secondary sure sounds like an open to me.
::Lewis
::
::
::
::
::Doug,
:::
:::There is 15 ohms across the pri and 47K across the sec winding. I opened the can and replaced the 47k resistor which was reading 61k.
:::
:::I've swapped the 6SA7, 6SK7 and 6SQ7, no changes.
:::
:::I have tried jumping both IFs with a 200 pf cap, it increased output slightly when I jumped the 1st IF, it had no effect on the 2nd IF.
:::
:::A friend of mine re-capped this set and brought it to me when it wouldn't work. I found an ungrounded filter cap, a couple of bad solder joints a lot of resistors that had drifted high, a bad rectifier tube (this set uses two) and a bad 6SQ7. After correcting all that, I'm left with this problem.
:::
:::I haven't opened up the first IF, the only thing inside are some micas. Could one of them be the culprit?
:::
:::Best,
:::
:::Bud.
:::
:::
:::
::::Bud, what resistance do you measure across the pri and sec windings of the 2nd IF xfmr?
::::
::::Might try a known-good 6SQ7, if you have one, but if not, don't buy one.
::::
::::Try jumpering across the 2nd IF xfmr with a 200-pF cap, per this suggestion: http://antiqueradios.com/chrs/journal/transformers.html
::::
::::Did you have this problem before recapping, etc?
::::
::::Here is the schematic: http://www.nostalgiaair.org/PagesByModel/012/M0008012.pdf
::::Doug
::::
:::::Hello,
:::::
:::::I've recapped and replaced out of tolerence resistors, checked tubes and ensured all circuits have continuity. I can push a BC signal through with the SG turned up, but it is up high enough that it should bast me out of the basement.
:::::
:::::The signal drops dramatically at the secondary of the first IF. Alignment improves but does not bring the signal up to normal. Voltages are normal throughout the radio.
:::::
:::::Placing my oscilloscope probe on the IF leads increases the volume significantly but the secondary of the first IF remains much weaker than the primary.
:::::
:::::I've eliminated tubes, caps, resistors, incorrect wiring, open coils, I've run out of options. Anyone have any ideas?
:::::
:::::Thanks for any help.
:::::
:::::Bud R