8MM-16MM FORUM WORLDWIDE

Steve, how can I find the right motor to match this one. This motor has no markings on it. Wouldn't you have to know the rpms for this motor?

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RPMs are probably 3600, since it's an AC motor. Beyond that it would be things like dimensions, shaft diameter and mounting locations.

If you could find a local shop with the knowledge and show it to them, they might say "OH! One of these!" (or "Where did you find THIS?!!")

I am at a dead end with this motor. Well, not literally, I'm in my screening room with the darn thing. i did find another Kodak Sound 8 and will continue the experiment when it arrives.

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Yes, This could be one of those times to find another (or maybe several...) machines and start picking and choosing the best parts from each, then cross-breed all the best stuff.

Hello Dan!

1) The resistor posted upstream is the bleed off resistor for the lamp socket- R1 in the circuit diagram. It drops the voltage sent to the lamp socket to lower the brightness of the lamp.

2) Have you pulled the motor apart? Remove the two nuts and bolts going through the frame and remove the two armature bearing end supports. Pull the support off the long extension side so that the other side will stay attached when you pull the armature from the stator- that will allow the rubber pulley to stay on the armature spindle and not have to be removed. Once removed, check for oxidation or signs of rubbing on the armature. If you find any oxidation, take a rubber eraser and scrub the armature. If there is no galling or pitting, the rubber eraser is abrasive enough to clean the copper without hurting it. If you see signs on rubbing or galling, the armature needs to be recut and new bearings installed- realistically, more expensive than the motor is worth.

3) Do you have a multimeter? Check the resistance of the motor. If you get a low resistance, the windings are good. If you get 0, open, infinity, etc- the windings are broken and open. If you get a very high resistance, the windings are shorted at some point.

Now, as to a replacement, you have a couple options. A, you can find another projector with the same motor and put it in place, or B, you can adapt a more modern motor. You might be able to find an AC motor that fits, but I would think it would be easier to fabricate a motor mount for a DC motor. DC motors develop better torque for their size, so you should be able to find a DC motor about half the size of that one- like what is found in a VCR drive- that you can fab a mount for. From there, all you'd have to do is integrate bearing blocks into the mount with oilite or needle bearings and place the armature from the original motor in it's original place. I would turn down the armature and make it into a pulley for a rubber band drive. Given the right lathe, you could also cut a bevel gear into it and make a matching gear for the motor so you don't have any losses due to band stretch, etc.

On further thought... it would appear option B is not really much more cost effective. Unless this is a very special projector for you, or a project you'd rather die than leave incomplete very long- I know what that feels like- your best bet might be to put it on the back burner until you find an identical replacement. The difficulty isn't going to be finding a matching motor, it will be finding a matching motor with the same shaft length and size as what is existent on the current motor. Motors in general are/ were universal, but manufacturers commonly ordered a special shaft length or size to fit their application.

Hope that helps a little,
Michael

Edited to add- PS- if you go with a DC motor, you'd also have to integrate a small transformer.

Additional PS- I've often thought it would be neat to integrate a DC motor as the drive motor in a projector- in doing so, you'd also be able to integrate a variable voltage circuit to adjust the drive speed of the motor. That way, you'd be able to fine tune the run speed of the projector to compensate for wear in the drive system or adjust for variances of speed in the original film recording if it wasn't timed in post.

-Michael

Michael, your expertise is overwhelming! Wow, with all the info I have gotten from you and everyone else, my work is cut out for me. I'll try to clean the motor per your instructions and see what happens. I'll check the resistance too and other trouble shooting tips. I do have another Kodak Sound 8 arriving tomorrow.

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So, I am sitting at my computer and an idea came to me. "I wonder what the little motor in my bathroom fan looks like?". I just climbed up on the toilet seat and pulled the cover off the fan and holy Toledo! It looks just like the motor in my Kodak Sound 8. Do you think this type motor will work??

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