Hello! I have a broken switching power supply. I accidentally push a striped wire inside the case and made a connection from FET heatsink to the case. The FET heatsink is connected to the ground of a input bridge. FET case is totally insulated from heatsink. It's a 5 and 12 V Traco power supply. I shorted out thermistor and polyfuse, remove varistor and replace broken bridge. Then I tried it on a autotransformer. The current was low at the beginning of rising voltage, but then if it just went up and burned the resistor, which is connected between source and bridge ground. I removed the FET and tested it. My AVR tester recognized it as double diode. The method with DMM failed and also method with 5 V power supply pot and 100 Ohm resistor, there was no current going into the drain. Does anyone have experience on that case, what can also be a common problem? Is there any common replacement for mdf7n60b FET, because this one is kind of hard to get.