"Cursitor Doom" wrote in message
...
Hi all,

Well, having established that the mains filter had fused and having cut
it out of circuit, I was advised to reconnect the supply to the scope and
whack up to full volts from the mains supply. I did this through the
variac I'd recently acquired and that seems to have blown it, I'm sorry
to say. Not the variac so much as my false assumption that a variac is
simply a jumbo-sized rheostat that when turned up to maximum could only
output no more than its input. Big mistake! I reckon I applied about
10-12% more than the smps's design voltage of 230V to it and now
something else has gone phut. No smoke, but a distinct sizzling noise
that lasted about 5 seconds before petering out.
So the question now is, what type of component is least likely to be able
to tolerate this marginal over-voltage?
thanks,
cd.


Is there a zener diode across any of the secondary supplies? Often these
short when the supply loses regulation.

Mark Z.