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NPR Problem


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#1 Tim Terner

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Posted 12 March 2009 - 03:41 AM

The stopping positon after a take is not always in the mirror position. (probably 50 percent of the time). The motor obviously has a park position that should be on the mirror position as when inching forward manually it takes you to the same position it had before. I've tried taking the motor off and inching to the centre of the mirror position (which it will do with the motor removed), replacing the motor and trying again, but same 50% of the time parking on mirror position and 50% not. Bloody frustrating as the motor has to be taken off every time to manually centre the mirror to get to a 'focusing position' Any suggestions ?
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#2 Olex Kalynychenko

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Posted 12 March 2009 - 04:23 AM

The stopping positon after a take is not always in the mirror position. (probably 50 percent of the time). The motor obviously has a park position that should be on the mirror position as when inching forward manually it takes you to the same position it had before. I've tried taking the motor off and inching to the centre of the mirror position (which it will do with the motor removed), replacing the motor and trying again, but same 50% of the time parking on mirror position and 50% not. Bloody frustrating as the motor has to be taken off every time to manually centre the mirror to get to a 'focusing position' Any suggestions ?


I do not know of NPR motor, but, i wish give you a some my ideas .

I know very good of similar problem with original electronic of 17EP-16 APK motor of Konvas camera.
This is motor have optical sensor on output axis with bulb and photodiode.
From other side, the axis of motor have disk with cut.
The system to read of signal from photodiode and control of parking function.
I repair of many original electronics of 17EP-16 APK motors and the every electronics have " personal" condition of parking functions.
The some motors parking of shutter for 2...3 turns, a some for 5..8 full turns.
The condition of parking very depend on output axle load.
The camera with film had better parking function from single motor only.

The detailed study of parking function give me idea to control of forms of signal from sensor and output signals of next chips at scheme of parking function.
But, at final, i have excellent parking functions with new, modern microprocessor system only.
And any my experiments with original electronics do not give me of essential distinctions.
I hope, this information can help you from "theoretical side".

You need go from waveform and signal swing of parking sensor.
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#3 Tim Terner

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Posted 12 March 2009 - 04:50 AM

Thanks Olex. So a motor malfunction rather than a camera one
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#4 Bernie O'Doherty

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Posted 12 March 2009 - 06:06 AM

Hi Tim,

Try taking the camera off the motor and testing if the motor stops in the same position by itself. You may have to put a slight drag on the motor driveshaft with your thumb and forefinger.
If the motor always stops in the same position, then you can assume it's the camera coupling that's the problem. The rubber coupling is probably worn.
Enter Shrink Tubing center stage. Go to Radio Shack/Electronic Store and find some shrink tubing that will fit over the Motor coupling. Cut a piece off and place it around the shaft. Use a hair dryer to shrink it. Fingers, legs and eyes crossed, your problem will disappear.
P.S. New motor couplings were last spotted in the Neolithic Age.
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#5 Tim Terner

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Posted 12 March 2009 - 07:57 AM

Hi Bernie, Followed your guidance and tested the motor and it was stopping at more or less the same place (within an arc of perhaps 8 degrees). So tried what you suggested (but with a bit of masking tape as no shrink tubing on hand) and it parks every time now on mirror position. Off now to try and find some shrink tubing. Really appreciate you taking the time to help and many many thanks
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