Mamiya M645 Slipping Advance Knob

[wjlapier]

I've had this Mamiya M645 for a while. I never really got around to shooting it after I noticed occasionally the frame advance knob would slip another rotation every once in a while. It happens anywhere in the roll--near the beginning, middle or end. The camera needed light seals so I put it away. I have a kit from Jon Goodman so I will install those eventually. I was wondering how prevalent is the slipping I mentioned? Is this something I could fix easily if I knew where to look? Another bit of info, it seems when it finally does slip the film doesn't advance more as I rotate the knob a little more to the stop--if you know what I mean. Basically, the film will advance as far as it should, but won't advance any further when the knob slips and I have to rotate it to the end of it's rotation.

 

[jvo]

yup, you got a problem... depending on the model, most winders easily come off. if so, maybe its a problem with it, or the plate underneath?

otherwise it needs qualified repair.

 

[paul ron]

is it just the knob and not the focusing mechanism?

If its just the knob slipping... try figuring how to take off the knob and re tighten the lose screws?

 

[darkroommike]

I have a 645 with the same problem and the camera seems to wind on to the first frame but the slippage puts the first couple of shots on the backing paper, lucky to get 13-14 shots per roll and that's not good. A CLA is the proper cure but may cost more than the camera did.

 

[paul ron]

I have a 645 with the same problem and the camera seems to wind on to the first frame but the slippage puts the first couple of shots on the backing paper, lucky to get 13-14 shots per roll and that's not good. A CLA is the proper cure but may cost more than the camera did.

so yours has slippage in the wind mechanism, not a lose knob. thats a different story and a different cure.

 

[darkroommike]

so yours has slippage in the wind mechanism, not a lose knob. thats a different story and a different cure.

Isn't the knob part of the wind mechanism? The knob comes off easily and can be replaced by either the motor drive coupling or the crank. If when the knob crank is folded out at 12 o'clock look for a black button at about four o'clock and put a fingernail or small screwdriver in there. Then turn the knob a bit, it should fall off. It's a bit more fiddly to put back on.

 

[paul ron]

if the knob mount is lose, it can slip on its shaft. if its a gear or other parts in the focusing mechanism its a different problem.

 

[wjlapier]

Lets see if I can explain this better. The knob can advance the frame and usually does so without slipping. But randomly. it slips after the frame is advanced but as it's slipping it isn't advancing more frames than the one. So, take a picture, rotate knob to next frame and the knob rotating stops. Take another picture then rotate the knob to next frame, but then after it stops at the end of it's rotation it turns one more time--360 degrees. Randomly. I'll look at the knob again and see about removing it, or tightening it. Other than that, the camera is very nice. Needs light seals which I have a kit from Jon Goodman and I'll install them eventually.

Thank you for the replies.