02-28-2016, 06:49 PM
From my repairman:
I am still working on the problem. If I pull the bottom output 6F6, (on the schematic) the sound is fine. With both tubes installed, audio pops loud especially as the volume is increased and especially with music. If I pull the bottom tube (on the schematic) 6F6 the audio sounds fine, put the other one in and volume increases slightly, but as soon as I increase the volume loud popping starts up with the audio and music. I made a post on Videokarma about the problem under antique radios, hoping someone has an idea. Schematic doesn't make much sense to me, and I have replaced all the resistors and capacitors in that section. I tried reversing the leads to the ends of the audio output transformer and it's the same thing. I don't even see how a signal can be sent to the bottom 6F6 (on the schematic) as the center of the 2 resistors between them is run to the centertap of the power transformer. Also I have no idea what the .01 capacitor is doing between the screen grid of the tube on top to the control grid of the bottom tube. Other than that audio sounds great with only one tube put it. (the top tube on the schematic). If I just put in the other 6F6, (the bottom on the schematic) with the top tube pulled I have no audio at all. I don't see any way the bottom tube can even receive a signal from the 1st audio, and sometimes it just looks like an extra which is suppose to do What? I am completely dump founded. Although the 1st audio (6K5) is somewhat micro-phonic, I don't think that is causing the problem. Maybe someone on VK will have an idea.
Addendum: I was wrong when I posted -15 volts. I just got done measuring it and it's a bit above -3 volts. Maybe I have a power supply problem. Will do some more checking.
This is just to better describe the problem.
I am still working on the problem. If I pull the bottom output 6F6, (on the schematic) the sound is fine. With both tubes installed, audio pops loud especially as the volume is increased and especially with music. If I pull the bottom tube (on the schematic) 6F6 the audio sounds fine, put the other one in and volume increases slightly, but as soon as I increase the volume loud popping starts up with the audio and music. I made a post on Videokarma about the problem under antique radios, hoping someone has an idea. Schematic doesn't make much sense to me, and I have replaced all the resistors and capacitors in that section. I tried reversing the leads to the ends of the audio output transformer and it's the same thing. I don't even see how a signal can be sent to the bottom 6F6 (on the schematic) as the center of the 2 resistors between them is run to the centertap of the power transformer. Also I have no idea what the .01 capacitor is doing between the screen grid of the tube on top to the control grid of the bottom tube. Other than that audio sounds great with only one tube put it. (the top tube on the schematic). If I just put in the other 6F6, (the bottom on the schematic) with the top tube pulled I have no audio at all. I don't see any way the bottom tube can even receive a signal from the 1st audio, and sometimes it just looks like an extra which is suppose to do What? I am completely dump founded. Although the 1st audio (6K5) is somewhat micro-phonic, I don't think that is causing the problem. Maybe someone on VK will have an idea.
Addendum: I was wrong when I posted -15 volts. I just got done measuring it and it's a bit above -3 volts. Maybe I have a power supply problem. Will do some more checking.
This is just to better describe the problem.
