Thanks to a very generous gift from John, I’ve been given an Amiga 1200. Even before switching it on, I’m going to take it apart, because these machines are 30+ years old. and who knows what lurks beneath the casing? Computers of this vintage are prone to leaking capacitors (and early 90s Amigas used cheap surface mount caps that are especially leaky), so they are bound to need replacing. Thankfully the A1200 didn’t come with a Varta battery, so there’s a good chance that the PCB is still intact.
A quick inspection shows an unusual looking card in the expansion slot. (The slot cover itself is missing, but it’s no great shakes to 3D print a replacement.) Some research suggests that it’s an FPU card, made by Elbox but branded as Power Computing. It has a 68882 FPU clocked at 40MHz, as well as 4MB of Fast RAM and a battery backed clock (CR2032 coin cell, not a nasty nicad!). Sweet, but I’m going to put it to one side for now.
Investigating the innards, the main board looks clean, and there’s no obvious sign of corrosion. But as mentioned above, I’ll replace the caps as a matter of course. I have a kit from Amigakit with all the requisite capacitors.
The recap goes almost to plan. There is one pad that detaches from the motherboard, and consequently a bodge wire needs to be fitted to one of the replacement capacitors.
The Amiga 1200 is reassembled and plugged in. It boots to the workbench with no problem. But there is a snag: the mouse only works in the horizontal direction. Vertically it’s pegged to the top of the screen. The problem is not with the mouse (I confirm that with a known good mouse), so there has to be an issue with the computer. I disassemble it again, and…
For that you’ll have to watch the video (I’m not ‘spoiling’ everything here, lol)
Thanks to PCB Way for sponsoring the video. They make excellent PCBs and a whole lot more. Check them out at https://www.pcbway.com/ (plus, be sure to check out next week’s video – we’ll be designing a PCB from scratch.)