Hey guys I am trying to troubleshoot a punch 801S the issue is no audio output powers up but has no sound on either channel. What are the four TL07C’s duty? Could a defective one be responsible for no audio output. I’ve used a similar RF amp to compare readings everything looks similar…
If it's producing rail and regulated voltages, it's more likely an input to the LM339 that's not allowing the output stage to be biased on.
DCV on pins 8, 9 and 14 of the LM339?
DCV on pins 8, 9 and 14 of the LM339?
Using an LM339 ( a comparator, for chrissakes) for regulation duty? That's insane! More likely it's a cheap and cheerful opamp (very cheap, not too cheerful) like an LM324
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Post #3: It's used in the protection circuit. Pin 14 controls the differential current switching. My 801 diagram is unreadable. The 501 is close enough to see what they're doing.
#4:
Those are not as they should be. Copy and paste this list and the DC voltages on all pins of that IC. Confirm that you are using a good ground for the meter.
Pin 1:
Pin 2:
Pin 3:
Pin 4:
Pin 5:
Pin 6:
Pin 7:
Pin 8:
Pin 9:
Pin 10:
Pin 11:
Pin 12:
Pin 13:
Pin 14:
#4:
Those are not as they should be. Copy and paste this list and the DC voltages on all pins of that IC. Confirm that you are using a good ground for the meter.
Pin 1:
Pin 2:
Pin 3:
Pin 4:
Pin 5:
Pin 6:
Pin 7:
Pin 8:
Pin 9:
Pin 10:
Pin 11:
Pin 12:
Pin 13:
Pin 14: