Re: 577 AC collector supply not reading zero on display

Chuck Harris

I seriously doubt that there is anything wrong with your variac.

If it had a part of the winding that was shorted, it would get hot
and hum and smoke quite spiritedly.

If it had a part of the winding that was open, it would either
put out no voltage, and then at some position the voltage would
suddenly appear, or it would put out normal voltage, and at some
point the voltage would disappear.

The windings are single layer, and spaced. Leakage is highly

-Chuck Harris

DW wrote:

Thanks, the replies are appreciated.

Chuck, you are right, I should measure from the wiper to neutral to get a more appropriate reading.

I have a parts 577 I am thinking about swapping the variacs out of and see what that does if I can't make any progress. I read somewhere on a forum that it is possible to fix a variac with a burnt winding, just solder a bridge to the next winding, but as Chuck mentioned about the wiper essentially shorting the winding where wiper is, that may not work to well when the solder gets hot from the current and fails.

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