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Servicing Motors?


Alan Rencher

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I have an FMG.6 Motor that will loose calibration and drift to one side of the lens. Some suggested that it might be the potentiometer. My question is: does anyone service or rebuild these motors?

Try another cable before thinking of servicing that motor.

Best!

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Hello Alan,

 

If the motor does not chatter it is most likely not an issue with the potentiometer itself.

 

Based on the symptoms you are decsribing it is likely that the friction clutch that transfers the motor output gear postion to the potentiometer

needs to be tightend.

 

The way these and most other analog motors work is that they have a motor with a gearbox attached and on the output side of that gearbox

There is a potentiometer that provides an analog output that represents the output position of the motor gear. Most of these potentiometers can only do one full rotation ( some 3 rotations ) and thus they need to have mechanical endstops that prevent the potentiometer from "rolling over " and thus confusing the control system as to which direction the motor just moved. The large amount of torque available on the output side of the gearbox is more than enough to break the endstops on the potentiometer thus manufactures employ a friction clutch.

 

As long as the friction clutch is tight the potentiometer will accurately track the output gear of the motor. When the clutch slips Before the potentiometer reaches it's endstop it will no longer track accurately ........ Thus causing "drift"

 

Hopefully this explaination will assist you in being able to service the motor yourself as I do not know of anyone that services these motors

 

Regards

 

Marc

 

-- excuse the spelling on my iPad

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No Problem Alan

 

Did you get it fixed yet?

 

Hope to see you at NAB

 

Marc

 

Unfortunately, 16x9 no longer services those motors as parts are no longer available. I might have to find a new motor.

 

NAB was fun, I guess I didn't see you though!

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If 16x9 doesn't repair these FMG-6 motors because of no parts available. Does it mean these motors aren't sold anywhere? I'm gonna have to dump mine before anything does go wrong with it!

 

These motors stopped being sold around 2002 when the manufacturer discontinued them. They resurfaced briefly when MK-V was selling a follow focus a few years ago but other than that they have been gone for years. 16 x 9 took the last few in stock and broke them down for parts so they could repairs the sold units but they started running out of some years ago.

 

Jim

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Don from Palomar/Loon bought my FMG.6 when I purchased my 2nd motor from him a few years ago. He was going to try to take up servicing them. He's a bit preoccupied now though...........

 

Dave Isern, soc

www.daveisern.com

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Don from Palomar/Loon bought my FMG.6 when I purchased my 2nd motor from him a few years ago. He was going to try to take up servicing them. He's a bit preoccupied now though...........

 

Dave Isern, soc

www.daveisern.com

I have 3 fmg motors, wich i only use for video lenses. The arnt strong at all, and the kind of suck with stiffer lenses. I bought a couple of m-one motors, wich are very very strong. Sometimes to strong. Anyway, if one of the fmg brakes down, it will end up in my garbage box, wont invest a cent in them for repairs. TO many good options these days. ( i must admit that the motors do preform fine for the last 4 years without any problems, the just aint thats strong )

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