Hi,
Just cleaning a three phase variac that was showing different L's and R's......i now see that the top coil's wiper comes off the coil track completely when you get down to the lower and higher voltage levels......so the carbon doesnt even contact one of the coils for a lot of the wiper track....only the middle of the track does it contact....other two coils are OK.
(ends of the coil)
Do you know what has caused this, and how to fix?....
Looks like the brass brush holder is getting stuck in the metal shaft piece...will file it down inside...and apply grease.
Any other tips appreciated?
I found this out whilst cleaning it...this was going to be my question, before the above became known....
(Just cleaning a three phase variac...just replaced the carbon wiper...and now its squeaky and a bit stiff and unsmooth as the knob is turned....is there any grease for this purpose?...obviously a non conducting grease.).
Also, do you know where to buy the wee carbon brushs?...its just a piece of carbon (graphite?) of dims 13.4mm x 9.3mm x 2.5mm