01-26-2011, 06:46 PM
AAAARRRRRGGGGGHHHHH!!!!! 
D**n it, that's what I get for having too many things going on at once...
Wil (Bill), I gave you incorrect information. I apologize.
I completely forgot that the 37-650 uses a "trick" audio circuit. To avoid using an audio interstage transformer, audio is fed from the 1st audio tube (6K5G) to the control grid of one of the 6F6G output tubes. Then, to achieve the phase inversion necessary in a push-pull audio output circuit, an out of phase signal is taken from this same 6F6G and fed to the control grid of the other 6F6G tube.
So, if you happened to remove the first 6F6G, you would have no sound. But if you pulled the other 6F6G while leaving the first one in place, you would still hear sound.
Therefore my original advice applies, which was:
When you replaced the electrolytics, did you connect the negative leads of (57) and (59A) to B- (center tap of the power transformer, and the ungrounded end of resistor (58) )?
Electrolytic (59) is drawn backwards in the schematic, also. The positive lead of this electrolytic (10 uF, 50 volts) should be connected to ground (chassis). The negative lead goes to B-. In other words, the opposite of how it is shown in the schematic.
Try those thoughts, take two aspirin and call me in the morning. I've got a migraine already.
D**n it, that's what I get for having too many things going on at once...
Wil (Bill), I gave you incorrect information. I apologize.
I completely forgot that the 37-650 uses a "trick" audio circuit. To avoid using an audio interstage transformer, audio is fed from the 1st audio tube (6K5G) to the control grid of one of the 6F6G output tubes. Then, to achieve the phase inversion necessary in a push-pull audio output circuit, an out of phase signal is taken from this same 6F6G and fed to the control grid of the other 6F6G tube.
So, if you happened to remove the first 6F6G, you would have no sound. But if you pulled the other 6F6G while leaving the first one in place, you would still hear sound.
Therefore my original advice applies, which was:
Quote:Other possibilities: bad ground connection(s), heater-cathode short in a tube, poor solder connections, miswiring/a component mistakenly soldered to the wrong place.
When you replaced the electrolytics, did you connect the negative leads of (57) and (59A) to B- (center tap of the power transformer, and the ungrounded end of resistor (58) )?
Electrolytic (59) is drawn backwards in the schematic, also. The positive lead of this electrolytic (10 uF, 50 volts) should be connected to ground (chassis). The negative lead goes to B-. In other words, the opposite of how it is shown in the schematic.
Try those thoughts, take two aspirin and call me in the morning. I've got a migraine already.
--
Ron Ramirez
Ferdinand IN
