Film-Tech Forum ARCHIVE: Christie AW3 Motor Problem

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Posted by Kerry Fleming (Member # 1657) on 08-22-2004, 12:02 PM:

Using Bodine motors on AW3 platter system.
Curious as to strange behavior when they go bad.
Seems the motor never just burns out and stops running.
When motor goes bad it will only run at constant top speed.
I read about carbon dust build up causing a short to ground.
Wondering why motor continues to run in this manner.
Seems strange for a DC motor!

Can they be rebuilt?
Know anyone who does rebuilding?

Thank you for your replies, advice, direction.

Posted by Mark Gulbrandsen (Member # 72) on 08-22-2004, 01:11 PM:

It soulds more to me like a shorted triac on the motor control card to me but carbon dust shorts are a sure possibility. Any decent motor shop can turn down the commutator, install new bearings and brushes. Let the new motor run in at 50% or less voltage for a couple of hours to seat the new brushes before using the rebuilt motor under load. A couple of extra points. Be sure the correct hardness of brush is installed so the cimmutator does not wear out prematurely, and have the repair shop install bearings with rubber seals on them so carbon dust cnnot get into them, especially the lower bearing. We do on the average of 15 to 20 of the AW-3 motors a month in our shop. Normal time is about an hour or a little more for the whole job plus run in time. We also rebuild the motor control cards as well.

Mark @ CLACO
CLACO Equipment And Service
1212 South State St.
Salt Lake City, UT
84110
801-355-1250

Posted by Darryl Spicer (Member # 711) on 08-22-2004, 01:30 PM:

Is this the Green motor or the black one. Why I ask is if it is the green one I would lean toward Marks second possibility if it is the black one I would lean toward Marks first possibility. You can verify that by plugging in the motor on a different deck and seeing if you have the same problem.

Posted by Bevan Wright (Member # 1884) on 08-22-2004, 03:10 PM:

Usually the build-up of brush dust takes 6-8 years, it is a good idea to blow these out yearly. The short usually takes out the motor card so swapping motors to a different deck is only advisable if you blow it out (and maybe change the brushes) first.

Posted by Darryl Spicer (Member # 711) on 08-22-2004, 06:48 PM:

the short issue doesn't always take out that card...at least it didn't 10 or 12 years ago when I last worked with Christie platters. You can take a good motor and verify if that card is bad.

Posted by Paul Konen (Member # 41) on 08-22-2004, 09:31 PM:

I have posted a picture on how the brush dust short looks like. I'll have to try and find it. Anyway, what I see happening when the black motor shorts out is that it will only turn in normal payout mode, not breakdown.

Paul

Posted by Kerry Fleming (Member # 1657) on 08-23-2004, 07:37 AM:

The motors I am speaking of are the black Bodine variety.
The motor control card is not effected.
I have replaced with another motor and speed control is normal.
The fact that this motor has floating brushes, and the negative
brush is not connected to ground, explains why the motor continues to operate and run at top speed. No one has cleaned these motors in years. I need to blow them out with compressed air a.s.a.p. Cheaper than replacements!