Holy crap, my apologies. I've been measuring pins 5-8 backwards.
Pin 1: -15
Pin 2: -.5v and climbing beyond -1v
Pin 3: -.5v and climbing beyond -1v
Pin 4: -15
Pin 5: -15
Pin 6: -10 and climbing
Pin 7: +15v
Pin 8: -15 0v
Pin 1: -15
Pin 2: -.5v and climbing beyond -1v
Pin 3: -.5v and climbing beyond -1v
Pin 4: -15
Pin 5: -15
Pin 6: -10 and climbing
Pin 7: +15v
Pin 8: -15 0v
There may be a broken connection. The end that's not connected to the TL071 must be connected to the secondary CT. Find the trace that's open and repair it. You can use a jumper for testing but you need to find the break in the original trace and repair it.
I don't see anything that is broken going to secondary CT.
One end of R46 goes to pin 6 of the U5 and the other goes to R43 and leg 1 of Q9.
Similarly, in the right channel, one end of R9 goes to pin 6 of U2 and the other goes to R6 and then leg 1 of Q3. Neither side for R9 goes to the secondary CT either.
The resistor is tucked just under an emitter resistor, correct?
One end of R46 goes to pin 6 of the U5 and the other goes to R43 and leg 1 of Q9.
Similarly, in the right channel, one end of R9 goes to pin 6 of U2 and the other goes to R6 and then leg 1 of Q3. Neither side for R9 goes to the secondary CT either.
The resistor is tucked just under an emitter resistor, correct?
R46 goes to pin 3.
On the other channel, it would be pin 3 of U2 to R11 to secondary CT. Check it.
On the other channel, it would be pin 3 of U2 to R11 to secondary CT. Check it.
Ok, it was R48 connected to pin 3. R46 is in fact connected to pin 6 of U5. R46 is hidden under the emitter resistor for Q30 (R70).
The through via at the end of the trace was connected to secondary center tap. The trace on top was burned so it was in fact disconnected.
I'll reconnect and test. Thanks a lot!
The through via at the end of the trace was connected to secondary center tap. The trace on top was burned so it was in fact disconnected.
I'll reconnect and test. Thanks a lot!
Sorry about that. The silkscreen on the amp I have photos of is not perfect and it looked like a 46.
Well, there is no more DC on either channel but the power AND protection LEDs are lit. The power supply fets get hot quickly.
If I increase the bias pots to their original positions it will attempt to come back out of protect, the transformer buzzes, then it goes back into protect.
If I increase the bias pots to their original positions it will attempt to come back out of protect, the transformer buzzes, then it goes back into protect.
As a side note I did locate another secondary CT trace that was broken and I have fixed that one as well.
How much current is it drawing when the power supply FETs get hot?
Were they clamped to the heatsink?
How long did it tame them to get hot?
Were they clamped to the heatsink?
How long did it tame them to get hot?
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