Konvas 17EP-16 APK motor runs fine, but stutters while stopping

[Geffen Avraham]

I recently tested a Konvas crystal motor I acquired with a 1M. I do not have a connector for it, so I ran it off a 12V 4.5A power supply, using two pins in the connector. It runs well, and measured with a tachometer does not drift.

However, when the motor is stopped, it stutters. It stops, restarts, stops, and starts again - about 2 to 4 times. Rarely, if I release the button softly, it might stop at once.

What can be causing this? Does it need more max current capacity that requires a battery?

[Dom Jaeger]

Sounds like a parking issue, not battery related. I’m not sure how a Konvas parks, but if it uses a motor encoder, I’d start there.

[Geffen Avraham]

It seems like in Olex’s videos, the motor also has the same stutter while stopping. It may just be normal behavior for these old Soviet motors?

 

Edited June 9, 2024 by Geffen Avraham

[James Compton]

Hi, Geffen. That on/off switch that you are using in the video is an aftermarket modification. It appears to be an electronic board issue. Contact forum member Aapo Lettinen. He repairs and upgrades Konvas motors.

 

[Aapo Lettinen]

16 minutes ago, James Compton said:

Hi, Geffen. That on/off switch that you are using in the video is an aftermarket modification. It appears to be an electronic board issue. Contact forum member Aapo Lettinen. He repairs and upgrades Konvas motors.

 

I had similar style motor years ago, it too had the "stutter" when parking the shutter. To me it looked like normal behaviour... one can make shutter parking couple of ways and to me it looked like the Soviets made a rough working one with it alternating "full on-off" modes until sensor shows good enough result.

one of the other ways to do it would be lower the power of the motor more when in parking mode. thus softer working but lower torque too which could cause issues if the camera has high friction.

one of the other ways is to run the motor at slow non-crystal speed but closed loop speed control still on. for example CP16R does this, runs at fixed 3fps until the parking sensor gives signal to stop. Softer working and still very good torque. more complex to make