Amiga defect!?

[spirantho]

What's the state of the Caps lock light? Is it on or off?

I seem to be cursed with A600s that the Caps lock light stays on for a full hour before cold booting... but they always eventually boot.

You could try just leaving it on for a few hours and see what happens....

(incidentally, I take no responsibility if you do this and your house burns down or something. )

[spirantho]

I've no real experience of dealing with knackered Amigas... but I've been fixing a lot of Sinclair Spectrums of late so I guess it's the same principles.

What I've done on the Spectrum is make my own diagnosis ROM which tells me what works and what doesn't on the motherboard. I don't see why you shouldn't be able to do the same thing on an Amiga.

The first thing I would do is burn a simple ROM with something like (pardon my asm, it's been a while):

START     MOVE.L    #$0000,D0
LOOP      MOVE.L    ($DFF180),D0
          INC.L     D0
          JMP       LOOP

Now from memory, and it's been a long time so I've probably got the syntax/numbers wrong, but this would just increment the background colour, resulting in multicoloured strips all over the screen - if the system is working. If this didn't happen, I'd know either the display was dead chip or the CPU was dead or not getting a clock signal. From there you can build more features into the ROM to test various parts of the system.

Again, I'm probably way off on the details, but I think the principle should be sound.

[spirantho]

I imagine any old EPROM and EPROM burner should do the trick. A simple 8K EPROM like a 2764 would work, but you may need to wire it up slightly oddly as the Amiga is expecting a 256KB or 512KB ROM, not an 8K one. I'm not sure what the pin-outs on the Amiga ROM chips are - they might be the same in which case you shouldn't need to rewire too much.

I wouldn't recommend it unless you at least understand basic logic circuits and about chip select lines and stuff... but then you're unlikely to own an EPROM burner if you don't.

Maybe someone else has actually done this...? I'm only working from a theory (though I think a good one).