The Amiga 600 Board I Never Quite Gave Up On
Pictures to come soon.
The first patient is the original motherboard from the "untested" Amiga 600 I bought from eBay back in January 2014 for £17.79. That price sounds almost silly now, but at the time it was just a faulty little Amiga 600 that turned up with one stereo audio channel not working.
That was the first sign that all was not well. Later on, the IDE connector also came away from the motherboard, thanks to the usual lovely mixture of capacitor leakage and corrosion damage. At that point, I did what most sensible people would probably do and bought a replacement board.
In March 2016, I found a replacement Amiga 600 motherboard on eBay for £36. It was described as an Amiga 600 Motherboard Rev 1.3 recapped, and that is still the board sitting inside my main Amiga 600 today. Around the same time, I also bought a 1MB Chip RAM expansion with RTC for £32.95, which was nearly as much as the entire replacement motherboard. That still makes me smile a bit now.
So the faulty original board was packed away. Not quite forgotten, but definitely moved into the "I will get round to that one day" pile, which is a dangerous place for old computers to live.
A Repair for the Sake of the Repair
I do not really need this Amiga 600 motherboard. That is the awkward bit.
I already have a working Amiga 600, and I am not trying to build another complete one at the moment. I have a replacement IDE connector in stock, and I would like to get the original board working again, but the main reason is simply that I enjoy the process. There is something very satisfying about bringing a damaged board back to life, even when you do not have a completely sensible use for it afterwards.
That is also why I am trying to be a little careful with this one. I do not want to keep buying parts until I have accidentally built a second full Amiga 600. A keyboard here, a floppy drive there, a case, shielding, screws, trapdoor, badges, and before you know it the "cheap repair" has become a small financial trap with a Motorola 68000 in the middle of it.
I may change my mind if someone starts making good new Amiga 600 cases. That would probably be enough to tempt me, because I am weak when it comes to this sort of thing. But for now, I am trying to keep this as a repaired spare motherboard rather than a full machine.
The Missing PCMCIA Port
There is also the small matter of the missing PCMCIA connector.
At some point, I salvaged the PCMCIA connector from this Amiga 600 motherboard to repair my Amiga 1200. I had damaged some pins on the A1200 while inserting the infamous Squirrel SCSI PCMCIA card, so the poor A600 board became the donor.
Looking at the A600 board now, it seems pretty obvious that I used too much heat when removing the connector. The PCB is scorched around that area, which is never a nice thing to see when you are looking back at your own previous repair attempts. After giving it a clean, the pins and traces look visually intact, but I have not yet tested continuity, so I am not declaring victory there.
A replacement PCMCIA connector is currently available from Analogic for around £40. That is useful, because many generic replacement PCMCIA connectors have shorter legs and may not pass properly through an Amiga motherboard. I am still undecided whether I actually need the PCMCIA port on this board, or whether I just want it fitted because the motherboard feels unfinished without it.
That is probably not the strongest technical reason to spend £40, but old computers do strange things to your judgement.
Testing a Loose A600 Without Buying Half an A600
One of the practical problems with a loose Amiga 600 motherboard is that it is not terribly useful without a keyboard.
I do not have a spare A600 keyboard, so I bought an AmiKey600 Amiga USB Keyboard Interface Adapter from Sordan.ie. This lets me plug in a normal USB keyboard, which is much more useful for a loose board on the bench than trying to source another original keyboard just for testing.
I have already used the AmiKey600 to test the board with DiagROM, so that purchase has paid for itself in usefulness. It is one of those small modern adapters that makes repairing these machines much less annoying.
I also do not have a spare internal floppy drive for this board, and I am trying not to buy one unless I really have to. If I need to boot from floppy, my external Gotek should be enough. I know the real floppy drive sound is part of the charm, but this board is not meant to become a complete nostalgia machine. At least, that is what I am telling myself at the moment.
The Music Player Temptation
One possible future for this board is as a dedicated IMP3 music player.
That idea keeps coming back because it feels like a useful halfway house. I could fit a hard disk or CompactFlash setup, use the spare RGB2HDMI adapter that came out of my other Amiga 600 after I upgraded that machine to an Indivision ECS V4, and maybe install my unused Furia 020 accelerator with 8MB of Fast RAM.
The Furia would probably be complete overkill for playing mods, but overkill has never really stopped me before.
I have also wondered about making it a caseless display piece, with the motherboard mounted where you can see it, playing IMP3 music and controlled remotely through a cheap KVM-over-IP adapter. It could sit there doing one job well, instead of me trying to justify a second complete Amiga 600 that I would probably not use very often. An ImpBox would let it connect to the internet.
Whether that is a good idea or just another rabbit hole with LEDs on it, I am not completely sure yet.
Where the A600 Repair Has Got To
For the repair itself, I have already removed the old capacitors. As expected, several pads were damaged, and I have repaired most of them so far.
The one remaining damaged pad is for the audio feed to the RF modulator. I have now removed the RF modulator because it was very rusty and I do not need it. I am not too worried about losing the RF output, but I do need to check properly whether any traces around that area have been damaged.
DiagROM 1.2 currently hangs during the Chip RAM test, so there may be another fault lurking on the board. The sound also does not seem to work properly without the capacitors installed, which may or may not mean very much at this stage. I did check the audio output pads, and both channels appear to be producing something, although one may be louder than the other. That would fit with the original fault, so the audio section definitely needs more attention once the recap and pad repairs are complete.
One of the leaking capacitors was in the audio section, so I would not be at all surprised if that area is where the real fun begins.
A Repair, Not Another Full Rebuild
So that is where this Amiga 600 board sits for now. I want to repair it because the process is interesting and because it feels wrong to leave the original board in a damaged state forever. What I am trying not to do is slowly buy enough missing parts to create another complete Amiga 600 that I do not really need.
None of this is meant as a recommendation to copy the exact same repair path. This board has its own history, including capacitor leakage, a missing PCMCIA connector, a damaged IDE connector and an audio fault that may or may not still be hiding in the same place. I will need to finish the recap, check continuity carefully, and see what DiagROM makes of it once the obvious damage has been dealt with.
For now, I am happy enough that the board is back on the bench rather than forgotten in a box. If I can get it cleaned up, stable, and maybe playing some mods through IMP3 one day, I will count that as a pretty good result.