John wrote:
I'm servicing an old PC switching PSU.

From the pictures, it looks like R2 (100 ohms) is across one of the
outputs - probably the +5 V output (red wires) - and 0 V / chassis
ground. This gives 0.05 A through it and 0.25 W dissipated. If it
really is a 1/4 W resistor, this is right at the limit, but
believable.

R1 looks like it is across the +12 V output and 0 V / chassis ground.
My guess is that R1 and R2 are there to provide a bare minimum load
on the +5 V and +12 V outputs.

Since R2 seems to have been OK originally, and it measured close to
the 100 ohm value you would get from reading the brown-black-brown-gold
bands and ignoring the white one, it seems reasonable that R1 would work
the same way: red-red-?-gold. You already found out that 22 ohms for R1
doesn't work. 220 ohms for R1 would give 0.055 A through it and 0.65 W
dissipated - too much for a 1/4 W, but maybe believable. 2200 ohms for
R1 would give 0.0055 A through it and 0.065 W dissipated - fine for a
1/4 W.

Have you tried measuring the original R1?

At a guess, I'd put in a 100 ohm, 0.5 watt resistor for R2, and maybe a
220 ohm, 1 watt resistor for R1. If you don't like how hot R1 gets,
maybe 2200 ohm, 0.25 watt for R1. I guess that a 22,000 ohm resistor
for R1 won't draw enough current to really do any good.

Matt Roberds