Zan FJ1295 washer odd fault

Went to a Zanussi FJ1295 washer (Pnc 914787016) which the customer had reported had “blown the fuse” with a “bang” (30 amp ring main trip, not an RCD) on two occasions about ten minutes into the “C” prog. Machine still working!

On inspection found no evidence of electrical blowout, no black marks, rear PCB OK, motor running sweetly and brushes OK, army meggered OK, etc. No low resistance showing on megger anywhere. Heater OK, timer looked OK (but not removed) both pumps OK.

Ran the machine with back off, and found that there was a fault in the heater supply – it would switch on (put voltage across the element) for about ten seconds, then turn off and stay off. The thermistor res was about 20K (same as a spare I had). Tried a 5K resistor in place of thermistor, same result – ten secs then off.

Otherwise machine performing OK on wash and spin. But no sign of cause of short circuit blowing trip-fuse.

Any suggestions???

Cheers.