[BBC-Micro] Master 128 Power Supply

[Richard Gellman]

Hi,

My Master 128 has developed a rather peculiar fault.

Onces its on, it runs fine. Getting it on however is proving problematic.

Flick the switch... nothing. Dead.  Take machine apart, all the 5v lines 
read 0.1 volts on the voltmeter. Try powering up supply separately, 5v 
lines now read 5v. Try reconnecting PSU to M128, switches on fine. Looks 
of confusion abound. Drink consumed, though sadly no alcohol present. 
Reassemble M128, and slide it back into position. Power on. Dead. 
RAMPANT looks of confusion now. Go to unplug unit, M128 suddenly powers on.

Its almost like the PSU has developed a random time delay before it is 
willing to provide power to the system.

Any ideas what might be causing this, or should I just give up now and 
swap it for the spare in the battered M128 that is (rightfully) buried 
in a cupboard?

-- Richard