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Macintosh 512k issues, R39? No video, rapid chirping when powered
Posted by: JohnnyPhantom on 2022-09-16 16:05:49
Hey everyone,
I just picked up a Macintosh 512k with its original power cable, keyboard, mouse for $100. I think it was a good deal. It was sold as-is/repair. When I power it on, I get no video or tone. I do get a rapid high pitch chirping. I already ordered a full capacitor kit for the logic board and analog board which are on their way. I opened it up and noticed a good amount of rust on the frame, but no board damage. The battery was removed before it did any damage. The battery holder is clean with no corrosion. When I power the machine on with the cover off, I see a highly suspect component. The R39 sparks and then gets toasty. It looks pretty burnt up, so I'll start with that and the caps and see if that helps. Only question I have for now is, what is R39 and where can I get a replacement? The analog board is part number 630-0102

Thanks everyone!
Posted by: Nixontheknight on 2022-09-16 16:06:39
Hey everyone,
I just picked up a Macintosh 512k with its original power cable, keyboard, mouse for $100. I think it was a good deal. It was sold as-is/repair. When I power it on, I get no video or tone. I do get a rapid high pitch chirping. I already ordered a full capacitor kit for the logic board and analog board which are on their way. I opened it up and noticed a good amount of rust on the frame, but no board damage. The battery was removed before it did any damage. The battery holder is clean with no corrosion. When I power the machine on with the cover off, I see a highly suspect component. The R39 sparks and then gets toasty. It looks pretty burnt up, so I'll start with that and the caps and see if that helps. Only question I have for now is, what is R39 and where can I get a replacement? The analog board is part number 630-0102

Thanks everyone!
the high pitched chirping means something is drawing too much current for the computer
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