How to test a Neve BA438 opamp?

[mjrippe]

Hmmm, this seems to indicate again that the opamps are fine. The voltage on pin 1 could be a cap installed backwards on the motherboard?

You still have zero audio passing through? Have you double checked the input and output connections? I have never seen this particular device in person so I don't have first hand experience!

 

[Golgoth]

Hmmm, this seems to indicate again that the opamps are fine. The voltage on pin 1 could be a cap installed backwards on the motherboard?

You still have zero audio passing through? Have you double checked the input and output connections? I have never seen this particular device in person so I don't have first hand experience!

I have recaped the motherboard and rewired everything as it was originally done. The polarity of the caps is checked. I have rewired both slots and I actually have a tiny amount of signal on the right slot, which is coherent when I swap opamps. The left slot is still terrible, whichever opamp is in.

 

[Coop]

Does the motherboard get it's power directly from the PSU? Maybe you can test what happens if you remove one board, hook it up to the supply directly and check voltages.

 

[Golgoth]

Does the motherboard get it's power directly from the PSU? Maybe you can test what happens if you remove one board, hook it up to the supply directly and check voltages.

I finally figured it out! The opamps were wired backwards. All 10 of them on both cards. Had I turned the unit on upon receiving it I would have noticed for sure. But I decided to disassemble it for cleaning first and trusted the original wiring when putting the circuit back together.

@mjrippe pinout drawing helped figure out the incorrect wiring! Thanks again!

 

[mjrippe]

@Golgoth Glad I could help, but you had to do all the hard work!