22 May 2024, 18:05 | #1 |
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Rev 8A 500+ Motherboard Trace Repair
Hello!
I was given an A500+ a while back. The battery had leaked badly. I've been slowly trying to get it back to life. Can someone verify where the trace shown in the attached image goes on the top/parts side of the PCB with a continuity meter? I've highlighted it with a pink rectangle. The trace goes towards Gary, but I can't find the end-point with my meter - potentially because the track is rotten. Unfortunately I can't find the schematics from this exact revision, so I don't want to make any assumptions before fixing the track. I'm guessing it goes to one of the pins on Gary, but even after pulling the chip from the socket it was all a bit obscured. (And my old man eyes are poor these days!) Thanks! |
22 May 2024, 18:21 | #2 |
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Note, I don't think you'll need the exact same revision of the A500+ to verify this - just an A500+ PCB without track-rot.
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22 May 2024, 18:28 | #3 |
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Use this: https://www.amigapcb.org/
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22 May 2024, 18:33 | #4 |
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22 May 2024, 18:34 | #5 | |
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Quote:
Edit: and yes, as suspected the track is bad. |
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22 May 2024, 20:03 | #6 |
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22 May 2024, 21:12 | #7 |
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Thank you both. Well I verified the LS244 that I replaced had all the correct connections, found that bad trace.
That being said, DiagRom still flashes green/red (bad chip memory). I'm waiting on a null-modem cable to see what the Serial output says. I'm not going to shotgun anything - this motherboard is very corroded which makes desoldering from it a nightmare. Not that I'm the best at desoldering, but it's easy to damage pads when the corroded pins are basically one with the PCB. Last edited by reassembler; 22 May 2024 at 21:17. |
23 May 2024, 11:46 | #8 | |
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Quote:
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24 May 2024, 11:10 | #9 | |
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Quote:
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02 June 2024, 23:11 | #10 |
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Fixed it. In summary: replaced the LS244 at U12. Had at least one dead output signal which was obvious using a logic probe.
Added about 6 or 7 bodge wires for damaged traces I found. Most were around U12, but also a bad trace from Gary too. I was shocked the audio worked fine on this Amiga, given the state of that section of the motherboard. I've also got myself some glasses, as my bloody eyes are shite these days - I'm a proper old man. nooooooooo |
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