On Dec 31, 11:34*am, "William R. Walsh" wrote:
Hi!

Can you hear a click as the motor gets up to speed?

I can now.

The motor in question was treated badly and left outside in the
weather. Rust soon covered the contacts of the centrifugal switch and
all of the electrical contacts. It couldn't work properly, so I took
it all apart and cleaned it. Even if you helped it, it didn't want to
run properly. More often than not it would just wind down and start
humming again.

Then the switch worked, but the motor almost always needed help to
start. After that it would run fine. So I started to look at the cap,
and $7 later it was replaced. All problems were then solved.

This is a converted fan, set up for standalone use wherever air flow
is needed. I have another that uses a run capacitor. It is much
fancier, with multiple speeds.

William

So, let's suppose you have a motor, and the nameplate is damaged to
the point you cannot see what size of cap is required. Where do you
go from there? I'm sure there must be a means of establishing that
you do have the correct cap. I found one document which states that
"the voltage across the cap should be about 5-10% higher than the
voltage across the winding, with the rotor locked." Has anyone any
other rules of thumb?