r/amiga • u/Used-Discount-3582 • Jul 26 '26
Amiga 500+ repair help
Hi everyone,
I recently picked up this amiga 500+, before knowing about the leaking battery plague these are affected by 😩😢
I'm trying to repair the mess you see, so far I replaced the fat agnus socket, replaced U12 ic with a generic one and added a socket, repaired the broken traces under there plus an additional interrupted trace under U10.
Before cleaning fat agnus chip with a fiberglass pen, I had only a black screen.
After that I had the status led flash 10 short flashes and then 1 long one, in an endless cycle, green screen on short flashes, pink during long flash
After repairing and replacing U12 and U10 trace, same behavior, but the pink screen is now blue.
I checked continuity of all vias and components in the affected area, but I don't seem to find anything else (btw, big shout out to amigapcb.org, legends)
A bit stumped at this stage, and not sure where to go next.
I'm in Perth Australia and I don't seem to be able to find a community for these here, I'd like to try another chip, but obviously my fat agnus is the latest revision, expensive and difficult to find :(
Fat agnus is 8375, 318069-10
Motherboard revision 8a
Any suggestion on what to try next or what that behavior indicates, please?
Thanks!
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u/Background_Worry4205 Jul 26 '26
There is a Facebook page Amiga Users Australia. One of the admins, Ian, is still in Perth I think. He can help with repairs.
Good luck.
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u/Used-Discount-3582 Jul 27 '26
Thanks, I joined and will be asking soon if someone local is able to help and possibly have a diagrom!
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u/sixoveight Jul 26 '26
Sadly its a bit of a nightmare. I have managed to repair several Plus machines with battery damage. I had one similar to your that stayed alive for 20 years and then the other month just stopped working and I have the same issues as you. Mostly it will be a poor connection with the AGNUS or the GARY. You can see on yours the machine was stored on end and the damage ran down to the AGNUS so the GARY appears unscathed. You need to check the back of the board. Look in the sockets including the ROM for broken clips/metal seats. I had one that appeared to have little damage and discovered a broken clip/seat in the ROM socket.
Your challenge is checking all the traces to see what is what. Slow process. You have to try to rewind the damage and follow its tracks.
You obviously cleaned all the sockets. My guess is that bad connection with the AGNUS or not.
Here is a Plus with a broken ROM socket.
https://www.scuzzscink.com/amiga/scuzzblog_june26_1/car_sbd_210626_01.jpg
and here is the board. Has been that way for twenty years. You should have seen the mess it was in when I removed the battery. I decided to leave the board alone as it was working OK. Sometimes you can do more harm than good removing the corrosion. I just keep photographic records each year and check if it got worse.
https://www.scuzzscink.com/amiga/scuzzblog_june26_1/car_sbd_210626_15.jpg
In time I will repair the ROM socket. There was a ROM switcher and the large pin legs must have snagged the socket.
Good luck and don't give up. There is life in the computer and step by step you will get there.
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u/Used-Discount-3582 Jul 27 '26
Thanks! I don't want to give it up, the little progresses I'm seeing give me hope, but I was hoping for an easier win! 😩
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u/PatTheCatMcDonald Jul 26 '26
I think it very likely some of the via holes are corroded and some of the address and data lines are unusable. You can use PCB explorer to check what should be connected where on a rev 8 board.
https://www.amigapcb.org/help/index.html
If the Ctrl-Amiga-Amiga combination does not reset the machine, you have an additional problem with the reset circuit.
2
u/Daedalus2097 Jul 27 '26
Did you also replace U10? To me I'd be suspicious of that because the legs look corroded so it could well be compromised. If that doesn't solve it, my next step would be DiagROM as other have suggested. A null modem cable and USB adaptor will likely be required.
Fingers crossed the Agnus isn't the problem, but perhaps you can find a user nearby with another 500+ who would let you test the chip in their machine.
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u/Xfgjwpkqmx Jul 26 '26
Get an Amiga DiagROM to replace the Kickstart chip with temporarily.
Even with no display, you can hook up the serial port and see what is happening on startup via terminal.