Ok, makes more sense except the no readings for R4 and Offset. What is meant by no reading? Let’s get the rail voltages too, but for the time being I will assume they are per schematic or close.
Depending on the remeasure of R4 and Offset, one or both of Q3 and Q4 are toast. That said, things still don’t quite add up and better diagnosis needs the remeasure requested.
Good luck
Depending on the remeasure of R4 and Offset, one or both of Q3 and Q4 are toast. That said, things still don’t quite add up and better diagnosis needs the remeasure requested.
Good luck
I don't want to be another cook in the kitchen...
See your measurements. Compare them back to the schematic you've posted. Look at the voltages suggested as operating points across R3 and R11. Compare them to your results for R4 and R12.
Note your observation that P1 did not alter the resistance measured across R5.
Does that give you an indication re: which "half" of the circuit may deserve more immediate attention?
Have you done precisely what Sangram has suggested? I, personally, would choose one path toward your troubleshooting and repair and follow that toward a conclusion.
I would also suggest politely that each measurement should be double-checked prior to reporting and that units should be provided with each measurement along with the power state. Yes, we know you won't see voltages with the power off, but it is important to know resistances with the power on or off and whether or not you have removed any parts per previous suggestions. It will help you and others to reach a speedy conclusion.
Good luck. I hope you resolve it quickly and are back to listening to music.
Stepping out to reduce the noise and multiple suggestions that could cause further confusion.
See your measurements. Compare them back to the schematic you've posted. Look at the voltages suggested as operating points across R3 and R11. Compare them to your results for R4 and R12.
Note your observation that P1 did not alter the resistance measured across R5.
Does that give you an indication re: which "half" of the circuit may deserve more immediate attention?
Have you done precisely what Sangram has suggested? I, personally, would choose one path toward your troubleshooting and repair and follow that toward a conclusion.
I would also suggest politely that each measurement should be double-checked prior to reporting and that units should be provided with each measurement along with the power state. Yes, we know you won't see voltages with the power off, but it is important to know resistances with the power on or off and whether or not you have removed any parts per previous suggestions. It will help you and others to reach a speedy conclusion.
Good luck. I hope you resolve it quickly and are back to listening to music.
Stepping out to reduce the noise and multiple suggestions that could cause further confusion.
There's something seriously wrong with your measurements. If they are correct it means the amplifier is gradually disintegrating every time you power on. I do not believe this to be the case.
Since it is very tough to refer back to your posted schematic every time, copy and paste the picture, and put in your measurements using Paint.
So what you've to do is, at the cost of repeating myself, is check P1 and Q5 outside the circuit and verify that they are working.
Then verify the JFETs are working, again, outside the circuit.
Then verify the power devices are okay, again outside the circuit. Simple ohmmeter and diode measurement will tell you which devices are okay. MOSFETs should show a body diode behaviour between drain and source, and infinite resistance between gate and any other pin. JFETs will have about 50 ohms between drain and source, and infinite from gate to any other pin. Transistors will show body diode behaviour between base and other two pins. Trimmers should show change in resistance when the turn screw is adjusted.
Now with all the devices out of circuit, measure each resistance, then post a schematic with your own numbers fed in. Removing the devices disconnects them from each other in this circuit and you can take measurements with an ohmmeter. Post all resistance and device measurements. Do not power on until you post and somebody who knows what he's talking about tells you what to do next.
Since it is very tough to refer back to your posted schematic every time, copy and paste the picture, and put in your measurements using Paint.
So what you've to do is, at the cost of repeating myself, is check P1 and Q5 outside the circuit and verify that they are working.
Then verify the JFETs are working, again, outside the circuit.
Then verify the power devices are okay, again outside the circuit. Simple ohmmeter and diode measurement will tell you which devices are okay. MOSFETs should show a body diode behaviour between drain and source, and infinite resistance between gate and any other pin. JFETs will have about 50 ohms between drain and source, and infinite from gate to any other pin. Transistors will show body diode behaviour between base and other two pins. Trimmers should show change in resistance when the turn screw is adjusted.
Now with all the devices out of circuit, measure each resistance, then post a schematic with your own numbers fed in. Removing the devices disconnects them from each other in this circuit and you can take measurements with an ohmmeter. Post all resistance and device measurements. Do not power on until you post and somebody who knows what he's talking about tells you what to do next.
I totally agree with ItsAllInMyHead’s recommendations. Let’s keep track of polarities of measurements. What is offset in relation to? Is there a load connected? Is the input connected? Would prefer measurements with input grounded and no load connected. What are the voltages of Q1 and Q2 gates with respect to ground? Measure resistance values while powered down.
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