You should have the same triangle waveform on pin 3 of U5 and U8.
Do you have audio on pin 1 of U4?
To confirm, you have 0v DC on the speaker terminals, correct?
Do you have audio on pin 1 of U4?
To confirm, you have 0v DC on the speaker terminals, correct?
U17:
Pin 1 - 0 volts
Pin 2 - +1.1 volts
Pin 3 - 0 volts
Pin 4 - -9.88 volts
Pin 5 - 0 volts
Pin 6 - +8.7 volts
Pin 7 - +10 volts
Pin 8 - 0 volts
Pin 1 - 0 volts
Pin 2 - +1.1 volts
Pin 3 - 0 volts
Pin 4 - -9.88 volts
Pin 5 - 0 volts
Pin 6 - +8.7 volts
Pin 7 - +10 volts
Pin 8 - 0 volts
BTW, when powered up, the output speaker + shorts to ground. Don't know if this is important or not.
That op-amp appears to be defective. With the inverting input (2) above the non-inverting input (3), the output (6) should swing negative, not positive.
I don't have that op-amp. Checking to see if I might have it on a board. I may have to order it to test. I'll post the results as soon as I can. Thanks Perry!
Okay, got the op-amps in today. Replaced U17. Output working some what. Found out U7 was bad also. In all, it took U 21, U17 and U7 to get the amp back up and running properly.
Thanks Perry for all the help. It was a learning experience for me. I'm much more checked out on this amp now.
Thanks Perry for all the help. It was a learning experience for me. I'm much more checked out on this amp now.
- Status
- Not open for further replies.