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Wait, can we use a bit more specific language here? I am a little confused.
In post #26 you state that both channels work separately but not together, then in post #28 you say channel A works but nothing comes out of channel B. SO either both channels work or channel B does not. We can;t have both conditions.
And again in post #30 "both channels work when I flip flop them." WHat does that mean?
Specifically, are you saying that if you substitute the various boards or subassemblies from the dead channel B into the good channel A the A channel continues to work? SOmething else.
I am not trying to be difficult, but we cannot interchange the terms boards and channels here. SO if you mean the driver board and power transisrtor module from channel B will work if wired into the channel A section, I can follow that, but let us call them boards and assemblies then and not channels. otherwise we might have a sentence like "channel B works in channel A," which might be clear in someones head while writing it, but not very clear to someone reading it.
Or maybe i am just getting too old...
So I will assume for the moment you mean the driver and power amp boards seem to work wherever they are, but when good boards are in the B channel wiring, no sound results. I then have to look at the signal between the input jacks and the driver board.
The input jacks send the signal up front to the volume control board - the little sqyare board the volume control lives on. Then from there nack to the driver board. All that travel by way of shielded cables. How do you find signal? You use a scope or an AC volt meter.. Get a strong failry constant signal of some sort. A signal generator is perfect - apply a volt or so of some nice clean sine wave. 1000Hz is a sort of standard test signal. I prefer 100Hz for general testing because i can listen to 100Hz a hell of a lot longer than I can listen to 1000Hz. 400Hz is another common test signal. But all I care about is can your meter read the signal voltage on its AC volt scale. Most modern DMMs will read up to 400Hz pretty well.
Measre the voltage right at the input jack of he amp to get a baseline reading. About a volt is fine. No signal generator? I usually use a feed from my little shop stereo receiver tuned to music stations. The signal may not be steady, but you can still see it on your meter. The volume control is a common thing. so is the signal present at the top leg of it? Top in the non ground end sense, not physically the top in the amp. The turning the pot up, is the signal now on the wiper too - the center leg? Then look at the schematic, follow the line from the wiper of the volume pot over to the first op amp. You can't measure at the op amp input pin, but is signal at the output pin? and the output of the next op amp?
In post #26 you state that both channels work separately but not together, then in post #28 you say channel A works but nothing comes out of channel B. SO either both channels work or channel B does not. We can;t have both conditions.
And again in post #30 "both channels work when I flip flop them." WHat does that mean?
Specifically, are you saying that if you substitute the various boards or subassemblies from the dead channel B into the good channel A the A channel continues to work? SOmething else.
I am not trying to be difficult, but we cannot interchange the terms boards and channels here. SO if you mean the driver board and power transisrtor module from channel B will work if wired into the channel A section, I can follow that, but let us call them boards and assemblies then and not channels. otherwise we might have a sentence like "channel B works in channel A," which might be clear in someones head while writing it, but not very clear to someone reading it.
Or maybe i am just getting too old...
So I will assume for the moment you mean the driver and power amp boards seem to work wherever they are, but when good boards are in the B channel wiring, no sound results. I then have to look at the signal between the input jacks and the driver board.
The input jacks send the signal up front to the volume control board - the little sqyare board the volume control lives on. Then from there nack to the driver board. All that travel by way of shielded cables. How do you find signal? You use a scope or an AC volt meter.. Get a strong failry constant signal of some sort. A signal generator is perfect - apply a volt or so of some nice clean sine wave. 1000Hz is a sort of standard test signal. I prefer 100Hz for general testing because i can listen to 100Hz a hell of a lot longer than I can listen to 1000Hz. 400Hz is another common test signal. But all I care about is can your meter read the signal voltage on its AC volt scale. Most modern DMMs will read up to 400Hz pretty well.
Measre the voltage right at the input jack of he amp to get a baseline reading. About a volt is fine. No signal generator? I usually use a feed from my little shop stereo receiver tuned to music stations. The signal may not be steady, but you can still see it on your meter. The volume control is a common thing. so is the signal present at the top leg of it? Top in the non ground end sense, not physically the top in the amp. The turning the pot up, is the signal now on the wiper too - the center leg? Then look at the schematic, follow the line from the wiper of the volume pot over to the first op amp. You can't measure at the op amp input pin, but is signal at the output pin? and the output of the next op amp?
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