8mm Forum: Motor Problem? Rank ALdis/Bauer SORTED

This is topic Motor Problem? Rank ALdis/Bauer SORTED in forum 16mm Forum at 8mm Forum.

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Posted by Tony Milman (Member # 7) on January 09, 2005, 02:35 PM:

Well, it had to happen sooner or later. Tonight the projector died and although I replaced the fuse that had blown it won't run. I think the problem is with the motor which is making a buzzing sound as it tries to turn but hasn't the power to do so. There seems to be power going to the motor from the transformer board (130V AC) and the motor in trying to turn is getting quite warm to the touch. No burning or scorching. The lamp works (so well it burned a hole in the film!)

I suspect there is a problem in the windings somewhere- anyone know if you can still get replacements for this model and direct me accordingly? [Frown]

UPDATE - I have found that by disconnecting the capacitor in the motor circuit and spinning the motor by hand it will spin up ok. It is still running very hot (is this normal?). Re-connect the capacitor and the problem is back. Could this be the answer??

[Frown]

Further Update

Yes it was indeed the capacitor which is clearly needed to start the motor and keep it running at full speed. Now replaced and running again
[Smile]

[ January 10, 2005, 12:05 PM: Message edited by: Tony Milman ]

Posted by Simon McConway (Member # 219) on January 11, 2005, 03:59 PM:

Hello, I'm not an expert with this motor, but know a bit about general motors, and those in B & H machines. I recall that motors used to be rated and given a "T Value" which was how hot they could get when normally running. Some of these motors you couldn't touch they were so hot, but they were still well under their given T value. On the B & H motor, it gets quite hot, but again, is still within its T value. What you must look out for is serious continuous arcing from within the motor. With any motor, you will get some, but you should never see anything continuous. That is a sign that rewinding is needed. So, just keep an eye on it. Try a new capacitor. But this is only for starting and will not affect the temperature of the motor. Hope this helps.

Posted by Tony Milman (Member # 7) on January 12, 2005, 01:11 AM:

Simon,
Thanks, Interestingly there is a heat shield around the motor so I guess that shows the expectation for running warm.

It seems the capacitor is also necessary for the motor to run as well as to start which is why when I was able to spin it up it was not running at full speed. The internet gave me some interesting information on inducction motors:-

Induction Motor-single phase

Oh, and I am sure Mr Elmo would want an acknowledgement for confirming all this! [Wink]

Posted by Barry Johnson (Member # 84) on March 08, 2005, 03:58 AM:

OK then gentlemen,heres one for you boffins.Its a projector motor,the make really does not matter but it starts off superbly then after 20mins the speed drops,quite noticeably to somewhere around silent speed,and yes,it is seriously hot-like you wont touch it!
Any ideas? [Frown]

Posted by Kevin Faulkner (Member # 6) on March 08, 2005, 06:54 AM:

Yes that could be down to faulty windings. Another possibility is that the Capacitor accross the motor which helps to kick start it in the right direction could be faulty. My money is on Faulty windings.

Kev.

Posted by John Whittle (Member # 22) on March 08, 2005, 10:12 PM:

I'm with Kev on this. I've seen it happen before, as the motor heats up, torque drops and then speed because the windings have shorted insulation.

In the distant past, people used to rewind motors. Don't know if anyone still does that today or if anyone still has the equipment around to do the job.

John

Posted by David Park (Member # 123) on March 09, 2005, 03:33 AM:

Here in UK one would look in the yellow pages section of the 'phone book. In my area book there are 3 rewiders/repairers listed under 'Electric Motor Rewinds and Repairs'. Hope your area has the same listing.

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