I think you'll have to keep checking voltages until you find something that's not as it should be. Start with Q4501-4504.
WOW look at all the post's for this amp! these sure seem to be problematic!
I have one I am working on as well. Thanks to PB for the service manual. Mine powers up, I get +/-47v, +/-15v, +/-5v, the Ucom 5V and the -10V Vss all come up just fine.
I get clean signal right up to the IC9701 opamp and that's where things go wonky. On pins 1 & 7 I get 5v DC and I get no signal, but every second or so I get a negative going spike. which i think is tied to the popkill circuit. If I look at Q4503 I get 5V on the B and E and on the collector I get 4-5v that wavers. so something in that area is not working correctly. I get all rail voltages on the opamps, hex inverters, and driver IC's just fine. the outputs are not shorted. etc etc.
The Output section is not running. so it must not even get that far in the power up sequence.
I have one I am working on as well. Thanks to PB for the service manual. Mine powers up, I get +/-47v, +/-15v, +/-5v, the Ucom 5V and the -10V Vss all come up just fine.
I get clean signal right up to the IC9701 opamp and that's where things go wonky. On pins 1 & 7 I get 5v DC and I get no signal, but every second or so I get a negative going spike. which i think is tied to the popkill circuit. If I look at Q4503 I get 5V on the B and E and on the collector I get 4-5v that wavers. so something in that area is not working correctly. I get all rail voltages on the opamps, hex inverters, and driver IC's just fine. the outputs are not shorted. etc etc.
The Output section is not running. so it must not even get that far in the power up sequence.
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