Recapped this analog board because it took minutes to charge up the caps and to get to a working voltage, however since recapping I only get the issue described in the title. The same issue occurs with and without the logic board, and I’ve also recapped that too. Any ideas?
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Mac Classic Analog Board - Clicking sound with oscillating 12v and less than 1v on the 5v rail
- Thread starter oliviaiacovou
- Start date
how would i go about testing these or do i just go ahead and replace them all?
Wait... Optocouplers can be tested with a diode tester? Is there something strange about that one?
Also, diodes don't leak and are possible to test.
Edit : ah, you mean leak current, sorry, I thought you mean some kind of fluid.
If they're leaking current you can test for that too.
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i already tested the opto and it seems fine, should the diodes have continuity going one way and not the other? just need to check because i can't find any working ones
How did you test the optocoupler?
Will do. Ordering those now, will update when I've got them all in
Just replaced them, no change
Welcome to the world of pain the Classic AB has brought to many lives as I documented here. Rooting for you to find a fix and watching as the problem is pretty much identical to the one I'm having.
How many caps did you replace? I recently did a couple classic analog boards, and I only replaced the caps indicated on recap-a-mac (as well as the two large ones near the flyback), and didn't have any issues. No diodes replaced, either. I suspect that the orange caps might be low ESR, so if you went scorched earth and replaced them, then that might be an issue. None of the ones recap-a-mac recommends you replace are, though.
I replaced only the ones on recap-a-mac, and I currently have the originals back in because I thought the ESR might be an issue, because I know the caps worked before, just slowly
I'm wondering if the sound you're hearing is the "flup" of the power supply repeatedly attempting to start and then resetting when it hits a failure condition. I think this term originally came from the book Macintosh Repair and Upgrade Secrets. If you search the web for "flup" or "flupping" you'll find plenty of relevant discussion.
the clicking comes from the speaker, would that still be the same thing?
See discussion of flupping that begins on page 117. https://vintageapple.org/macbooks/pdf/Macintosh_Repair_&_Upgrade_Secrets_1990.pdf
I replaced all of them, since I saw that shiny 'hey, I leaked' deposit all over the place. So I pulled them all, cleaned the board and replaced with new caps. I'm going to order new low ESR caps based on the list from Amega of Rochester (https://amigaofrochester.com/recap-services/capacitor-list/) which I didn't see before I did the cap work
