This Photos confirm a short from Collector and Base from heatsink if you use BU2508A without isolations, and probably is it damaged for this error, the EMITTER is coing to heatsink and COLLECTOR are shorted to EMITTER from heatsink.heres the heatsink clip:
View attachment 1274931
and heres where it goes on the board (for anyone interested ) oragne is where the tabs go, red is the 'pin' on the groupd clip (please don't look too closly at pin E just above, yes, I lifted a bit of the pad when initially de-soldering!)
View attachment 1274932
Sorry, from Collector and Emitter and not Base....my digit error....
I need to learn not to rush in when replacing components
So, the BU508AF turned up today, is this part a suitable replacement ?
View attachment 1275060
also got some freeze spray delivered today, I need to find a cap that takes a 'straw' as this just has the wide nozzle.
C2541 short circuit.
R3540 open circuit.
D6540 open circuit.
Transformer winding faulty (open or short circuit).
Something that -27V is connected to is short circuit.
Dave