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.