Hi!

Thanks for the feedback. I would not know where to find a replacement
fuse, given I'm living far away from shops where they sell them.

Most every computer power supply I've seen has used an AGC (glass) type
fuse. It looks like a tube with glass in the center and metal at the ends.
The rating and voltage will be printed (stamped) on one of the metal ends.

This Compaq power supply was from 1998, I hope back then it was
also designed to cope with short circuits like the new one I bought
now.

Normally a computer power supply will simply "crowbar" its outputs and shut
down without damage when a short circuit comes up. That's assuming that the
power supply is in otherwise good health with no components that are
starting to fail or change characteristics.

I suspect the red-black wires transport 12V supply, and the
yellow one 5V (?).

The red wire is +5 volts. The yellow wire is +12 volts. Each black wire is a
ground.

William