Amiga 4000 Repaired!

johntayloruk

Member
Joined
Feb 23, 2019
Posts
88
Country
United Kingdom
Region
West Yorkshire
Hey, just thought I'd do a post for a project I've been working on thanks to having lots of time with the lockdown.
I bought a non-working Amiga 4000 Motherboard on ebay, it was filthy, corrosion on many of the resistors, the battery had gone to work and had eaten its way through to the rear. I didn't want to even turn it on in the state it was is so I gave it a clean with white vinegar and IPA (my word the amount of fizzing and fishy smell...yuk ).

Anyway, I've had an ultrasonic bath I've been wanting to try for a while so I removed the caps and socketed chips and gave it a good soak. It came up like new and I could then see what I was faced with...:roll:

U177 (74HCT174) had pretty much been eaten away, hardly any pads remained and there were traces broken all over the place., particularly around the memory sockets going through the vias to the underside of the board.

The traces from the row of resistors around R982 to the jumpers at J975 were completely broken and had to be repaired.

The F245 chip at U891 had also been damaged and had to be replaced. Again that fishy smell when you get underneath...yuk!

Anyway....after many hours testing traces, re-flowing most of the board, replacing the caps and adding new simm sockets I turned it on and.....it only worked! I was so happy to see that WB 3.1.4 screen/ I did a full check with Chucky's Diagrom and all was ok. I used some solder mask to cover things and to secure some of the connections in place (probably too much), but it's working fine now!

I've had 10 of Chucky's A3660 boards made up so my next job is to put one together and then likely look to sell this as I have another original A4000 as well as a new one I've just made up!
 

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That is fantastic. If only a4000s were so easy to get in my region. I have one a4000 68030 non working atm and I really need to fix it. I am kind of scared touching the fragile traces and not to fsck up the whole motherboard since I have two left hands :D
 
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