Help; need FET sub

[preacherJohn]

make certain you can obtain the correct Voltages at the two Zener diode, the + and -24.5V.

I have the 24.5-9v on the Zeners. It depends on the orientation of the test leads to whether its a - or + voltage. I replaced the JFETs this morning, and I also matched an replaced the transistors Q1-4 on the pwr amp; I'm running right at 0 volts of the dc offset on the left channel, but about 55mv on the right. It was up in the 70s until I matched a couple of 992s. The left channel works normally now, but the right channel isn't working for some reason. Not sure what's going on with it yet. The biasing pots may have an issue. I'm looking there next.

 

[preacherJohn]

Bias on the left channel is good. There's no bias voltage at all on the right channel. Sheeze, now where to go? Guess I need to hook up the scope.

 

[Jose Jimenez]

Anything further? I have been doing yard work.

 

[preacherJohn]

Anything further? I have been doing yard work.

Still trying to chase down why I don't have a right channel now. The left side is really kicking butt. I found many out of spec resistors on that side and replaced them and the Qs check out. My wife blew a tire yesterday and took me away from the bench. It's getting kinda frustrating. It's gotta be something simple. All the electrolyics have been changed. I never checked the ceramics in it. And I don't have any that small around here. Not sure where I want to go next.

 

[Jose Jimenez]

I believe you mentioned that you had a o-scope so that can help tremendously, but I would compare Voltages to start on each channel. The must be some symmetry that you can observe and measure right against the left channel. You also have those key Voltages on the schematic. I was looking at it some but with the scope you could observe a signal and see where it stops in the circuit. Your phone can generate a sine wave if you do not have a generator.