Baron wrote in message
...
Smitty Two Inscribed thus:
In article ,
"Arfa Daily" wrote:
"Smitty Two" wrote in message
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Please tell me whether this is an inverter or a bridge rectifier,
if you recognize it out of circuit context.
http://members.cox.net/prestwich/51.jpg
Selenium stack bridge, by the looks of it. Equipment it's in ?
Arfa
Ancient European slide projector with rotary carousel. Trying to help
a friend get the thing going again, via email since he lives in
another city.
Problem with it is that this motor:
http://members.cox.net/prestwich/52.jpg
turns very slowly.
It didn't make sense to me that a rectifier would be fed by a motor
winding, but there you go. So now it seems the motor is 240, but
there's a secondary winding in there putting out about 17, and he's
getting about 12 VDC out of the bridge, so that part seems OK now.
Is there anything on that type (shaded pole?) of motor to fix, or is
it an R & R job? (remove and replace)
That is an AC shaded pole motor with a tapped winding feeding the
rectifier. It also means that one side of the circuit is directly
connected to the mains.
These commonly get glued up bearings. The cure is to strip it clean and
lubricate the shaft on both sides. Use only a very fine oil ! Sewing
machine oil is ideal. Reassemble. Job done.
The shaft should rotate freely without any binding. The only other
possible problem would be shorted turns on the coil ! But if that was
the case I would expect smoke !
--
Best Reagrds:
Baron.
Are shaded pole motors synchronous to the mains frequency unless overloaded
?
I was always surprised how much axial movement there was of the rotor
between the bearings, is this a necessary part of the design ? maybe to
assist startup as relatively low torque even when rotating.
In the present case could low revs be a consequence of a fault in the
electronics, via back emf? is the motor speed the same when the Se
rectifiers are disconnected , not just the electronics disabled?
--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/