OK, so the thermistor that rick's diagram says terminates defrost is not the same control as the bimetal? I may have missed it in the diagram but I don't see other leads coming back from this bimetal sensor to the board. or is it just in series with the Def terminal on the AC side rather than the DC control circuit.
and thanks for tip to look at location of resistors to identify different board.
there was definitely something cooked on the original board when I changed it and I left it sitting on my bench for 2 years in the box from the replacement board but can i find it today . . . nooooooo.
I didn't do the second replacement.
I think this thread was just starting up back then when I did the first and wish I had found it then because I would have had a better chance of tracing the cause.
Yes I understand power spikes are a problem generally although not really a believer that current surge technology can quench lightening level problems without damage to sensitive electronics although I think instability and switching on the grid can be controlled for.
But no other damage to electronics in this building and it returns me to my concern about having this stuff digitally controlled to begin with.
thanks, headed over there to have a look right now. Might have a little more info next time I post.