On 8/22/2010 10:43 PM, mm wrote:
On Sun, 22 Aug 2010 21:51:14 -0400, Jeff
wrote:

On 8/22/2010 5:34 PM, PE wrote:
I have an oscillating table fan that recently stopped working. I'll
probably just buy an new one, but wondered if anyone here might have any
useful suggestions. The fan's performance didn't degrade over time; it was
working properly and then suddenly it just wouldn't turn on. I've tested
the 4 way switch (Off-1-2-3) and it's working properly. And when the
control is switched to any of of the "on" settings, the motor doesn't even
make a humming sound and rotation can't be started by giving the fan blades
a shove, so I assume the problem is not with the motor starting capacitor.


Actually fans almost never have motor start capacitors, they have a
"shaded" winding to give them a kick in the right direction. The
starting torque required needs little more than that.

This is sort of related. I have an old 8 or 10 inch fan, -- to judge
its age, almost everything that shows is plastic -- and I use a remote
switch on a cord to turn it on and off, and a light dimmer to have it
run a little slower than speed 2 iirc. (at full speed 2, the noise
bothers me) When I had tried setting the dimmer below the current
setting, it wouldn't run at all, but it's been running at this setting
almost every day for hours all summer for 5 or more years.

Early this year, after I turned it, on it would run a quarter turn,
then slow to a stop, and could take up to a half hour before it got
moving again, first slowly and within a couple minutes the normal
speed.

This went on for 2 or 3 months, even on cool days, but about a week
ago, it stopped and now it turns on correctly right away. Like it
used to.

AFAIK, fans aren't supposed to run on ordinary light dimmers. They are
designed to run at some slippage (more slippage, more torque) off the
synchronous speed. You are sort of fooling with the slippage needed to
generate enough torque to run the fan by reducing the "power" in. I'm
rather amazed it "works", but what do I know!

There are special motor speed controllers, not that I know how they
work, but you may wish to try one.

Never hurts to work a little oil into the bearings (probably SAE 20
or 30 non detergent), perhaps it got a little gunked up and worked
itself free.

Then again, why argue with 5 years of working?

Just my take on it.

Jeff

LIfe is so strange.