Last week I confirmed that the over-temperature sensing cct worked and the
triac cut the supply to the mains transformer. This is a Carlsbro S600M I
can find no info on . I was running on a variac and with about 90 percent
mains and with no load etc there was 0.1 amp current drawn from the mains
and a noticeable amount of transformer noise I took to be saturation noise
and current drain, more than I'd like but until I could confirm with the
owner about previous useage, I let be for then. This time I powered up and 1
amp being drawn with no load at only 70 percent mains. Disconnected the
secondaries from the amp and still the same.
Disconnected triac circuit and the transformer is happy to 100 percent
mains, fed directly, and only few mA of current drawn. What can be going on
? To get to the triac componentry proper requires a major strip down first.
Could it be half cycle firing and causing some sort of magnetic
mutual/resonant/self-induction effect that is causing excessive current? A
matter of isolation transformer and scoping some dropper in line with the
primary to see ? No obvious heating on the triac, only a small heatsink. I
was monitoring the DC last week and it was already a bit over the 63V rating
of each electro. This time direct to mains, no triac, it was much more
normal, forgot to note but about +/- 55V probably at 100 percent mains