Macintosh LCII failure

[indibil]

Hello.

I haven't received any replies since my last post. Perhaps I didn't use the oscilloscope correctly; it was my first time, but I think it illustrates the problem.

Today I ran a test. I had the motherboard from an LC3 and swapped the two sound chips. The LC2 with the LC3 chip has the same problem, and the LC3 with the LC2 chip works perfectly.

So, if the fault is located further back from the measured point, and it's not the sound chip, what could be failing? A transistor? A ceramic capacitor?

I'm lost. Can anyone guide me?

Thanks.

 

[Garrett]

That's interesting that when swapping DFACs, the issue stays with the board, not the sound chip.

I had an LCII with bad audio once, and replacing the DFAC did solve my issue.