Strange voltages

[jeanmarie]

Allen model 90. W₩hy or what could cause measuring only 41 volts ac from the fuse to chasis?

 

[Tinkerbelle]

Presumably you have measured ~120V incoming and are expecting 120V. I assume it is not a 3-pin plug with chassis grounded to incoming ground. Which AC line is the fuse mounted in? Perhaps the fuse is in the return side, floating above chassis ground. If a 2-pin plug, does it read the same when you reverse it?

 

[jeanmarie]

The fuse is on the hot side, reversing the 2 prong plug does nothing.

 

[gadget73]

Try a 100K resistor to ground and measure across it. If you get nothing worth talking about, its likely very minor leakage from the transformer or induced voltage. A DMM is something like a 10M impedance, so you'll read voltages with extremely low current levels. If it still reads across 100k then it could be an actual problem.

 

[jeanmarie]

So measure from fuse to neutral of the PT?

 

[gadget73]

if you want to measure voltage input, yes.

I misread the original post, I was thinking you were measuring from ground to chassis and getting voltage.