I have an old single phase 110V 5.6amp 1/3HP 1200rpm induction motor
that operates a scroll saw..The motor ran well in the past but now it won't
start, it just sits there drawing current. If I spin the motor by quickly
the belt it will start.
It has capacitor start and the cap measures 84 mfd. Can't read the cap
rating printed on the cap clearly but it looks like its a nominal rating of
I'm assuming the cap is OK because I can measure what seems to be
a reasonable value.
Any idea what the problem could be?
Check out the start switch. Blow out any dust accumulated in the
motor. I've had dust shut down some of my non TEFC motors
in the past, but just blowing them out solved the issue.
Hope it helps,
Assuming that the capacitor is, indeed, good, it is possible that the centrifugal
switch is stuck open or has failed in some way.
"It ain't what you don't know that gets you into trouble. It's what you know
for sure that just ain't so." --- Mark Twain
Unplug the motor. direct some compressed air into the vents. Look inside
the vents, while rotating the shaft by hand. You may be able to see the
centrifugal switch assembly on the shaft. Carefully use a screwdriver to
push on the switch, it should go back and forth on the shaft.
Sawdust in the switch can jam it open, defeating the starting coils.
Cleaning it is good, but may not be enough. I had a motor that
started doing that and found that the contacts on the start switch
were badly burned. Light filing and polishing returned it to
operation, but burning and pitting are likely after a period as much
of the hard surface of one contact is gone.
A washing machine or dryer motor will work if you can't get the original
going. If the air doesn't work, taking off the end bell is not hard, then
you can see and clean everything. Take your time and don't bend the little
Put a little roof over the motor to stop some of the dust, if you can.
I have a VERY lightly used Delta 8 inch band saw that suddenly stopped
working yesterday. Flip the power switch nothing happens. I have a pipper,
and I can detect ac getting to the motor, but no action at all. Is this a
common thing? This thing really hasn't been used much, but did spend some
time in a damp basement.
It is a single phase 1/5 hp motor.
I really like this saw, but have only used it about 12 times in several
years (while my shop was being rebuilt). Now I really want to use it, and
it is dead. I don't dare try to start it by moving the blade. The
capacitor (I don't have a way to measure it) looks brand new. The whole
thing is practically brand-new.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.