A1200 crashes a lot when it hasn't been on for very long

[Karlos]

Could be a lot of things:

Power supply - The 060 draws less power than the 040, but such an expansion is still too much for a vanilla supply, especially iwith a HD installed. Are you using a higher wattage one?

Dirt - not saying your machine is filthy, but grime and muck always gets into connectors. Have you removed the card and the RAM, blasted any dust away, cleaned the connectors and put everything back as it was?

Heat - While the 060 is generally cooler than the 040, some XC models ran pretty hot. Is your system sufficiently ventilated?

Age - drying/leaky capacitors, dull solder joints, flat/leaky batteries. These are all sources of potential instability.

[Karlos]

It's an old A500 brick rather than the newer A1200 stock PSU.

IIRC, the A500 power bricks were rated at 60W, compared to the 23W or whatever it was the 1200 ones had. Don't forget, it might be the case that the PSU itself is suffering from old age too.

I should probably go over it with the air duster at some point, the floppy drive was playing up the other day as well, I blew in it and the disk was no longer unreadable :/

Dust kills. It can cause localized overheating, even in a cold environment. Then, there's the potential for dust to pick up an electrostatic charge.

The room is fairly cool, there is no radiator in here and it is Scotland in the winter!  If it was heat I'd have expected the problem to get worse the longer the machine was switched on, but the opposite is the case.  After it's been on for 15 minutes or so it's fine.

Cold can be an issue for old electronics as much as heat can. The above might indicate problems with connectors, though I'd expect most of the connections to be "tighter" when the machine is cold. Connection problems caused by dodgy solder joints, however, often get better as they warm up and expend.

I can take a look... not had the case open in a long time now though, but I was meaning to clean it some day so maybe now's my chance.

You'd be surprised how much crap can get inside, so it's worth giving it a clean.

[Karlos]

@MrsBeanbag

My A1200+1260 had similar problem many years ago circa 2000.

I traced the problem to a loose fitting connection of the Apollo 1260 to the A1200 MB.  The A1260 was at a slight angle due to gravitational attraction of a nearby planet (Earth).

Solution: Duct Tape!  Once I taped it in such a way as to support the board in a perfectly straight line I never had a problem again.  Its been 12 years and I never even had to replace the tape or or anything.

This may also explain why my towered systems are generally more reliable than my desktop ones. The card is never out of alignment with the motherboard.