Film-Tech Forum ARCHIVE: Motor heat on AA-II

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Posted by Brad Morris (Member # 1175) on 09-05-2004, 04:58 PM:

After having the original motor re-wound on a DP-70, I've noticed that it is running warmer to the touch than before the rebuild. The motor shop that did the work said that I didn't need the run capacitor any more due to the way they rebuilt it. Do those of you who are Norelco savvy have any insight into weather this is correct, or should that capacitor still be used? Also, what value should the capacitor be?

Thanks.

Posted by Mark Gulbrandsen (Member # 72) on 09-05-2004, 05:52 PM:

I have no idea how the motor shop you used actually rewound it. Most sync motors do require a start and run capacitor to function properly. There were three kinds of motors used on DP-70's and they and their proper capacitors are all listed in the Norelco Tech Servcie notes in the F-T manuals section. I would reccomend that you experiment with using different capacitors that were close to what was used in your situation and see how the temperature goes after say 8 hours of operation. Neither the Master or GE motors should get more than luke warm after an 8 hour day.

We have had sync motors rebuilt by shops with good and bad results and no shop ever gets the windings layed exactly the same as the original resulting in some power loss and heat generation..... So my feelings on getting a proper rewind job on a sync motor is pretty touch and go.

FYI, We no longer advocate having the original DP motors rebuilt. You would have been far better off installing a variable speed drive system on your DP-70... even if its a two motor machine as you can eliminate the second motor completely and set up the new drive system to run at what ever speeds you need. These vari speed drive systems don't cost much more than having the original motor rewound. There are many benefits to using these systems such as adjustable max current per phase shutdown, user adjustable run up/run down time, jog, and several other useful functions. Our vari-speed drive kit includes a Baldor single phase drive unit, 1/4 hp three phase Baldor motor, new motor mount, new direct drive coupling to eliinate the drive belt, and has an auto jog to threading position feature when the motor is comming to a stop. This sets the projector so you can open the cooling plate to re-thread without having to inch the machine over by hand. The auto jog feature is also much gentler on the mechanism than turning it over by hand!

Mark @ CLACO

Posted by Steve Kraus (Member # 476) on 09-05-2004, 07:22 PM:

Mark, just out of curiousity how fast have you run an AA-II?

Posted by Mark Gulbrandsen (Member # 72) on 09-05-2004, 08:10 PM:

No faster than 30fps at this point. I've not had any real reason to go faster but it should do 48 fps with 35mm easily. As for 70mm I would think that 48 fps would be easy for it but without the oxide stripes. These machines are used in quite a few places for 8/70! The mag stripping does cause alot more friction in any projector. I did the Century SA's with fast-foreword that would go 48 fps to get through alot of dailies print. They had no problem at that speed...... but much over that the loops begin to oscillate wildly. I've always that might be caused from approaching the resonant point of the loops themselves.

Mark