I am working on repairing a motor controller for a washing machine motor (120vac -> 220 VAC (3 phase). After replacing 2 shorted IGBT's (and that not fixing the board), I have started to trace paths and see what else was wrong, power input seemed like a good place to start. Right away I noticed that the two ac inputs for the bridge rectifier (d10xb60 https://www.mouser.com/datasheet/2/366/J534D10XB-1203178.pdf) are shorted together. To clarify, I don't mean the chip has been damaged, I mean those center pins are intentionally soldered to the same trace on the board. I have 2 of these drivers, different boards and it is done this way on both. This also leads to some very strange readings on my DMM (strange enough that I grabbed another DMM to ensure mine wasn't broken). By strange I mean: there is sometimes a volatge with only one lead connected, pin->pin i have 0v (as expected by the short), if I connect to one of the pins and then touch the other probe to the frame of the washer(presumable ground) or even just to my body, I see 120VAC. If I look at the dc output pins, I see like 345vDC.
So my questions are:
why is this done this way?
how does it even work with those two lines shorted together.
So my questions are:
why is this done this way?
how does it even work with those two lines shorted together.