Mamiya 645 shutter issue

[Chris Harvey]

Dear good people of APUG, I wonder if you could help solve a small issue I have with a Mamiya 645 Super camera?

I have sourced the components for this camera from a variety of places, currently it comprises of a 645Super body (in almost brand new condition), Power Drive N (again almost brand new), non metered prism, film back with 120 insert (unmarked) and a 150mm f3.5N lens. The batteries in Power Winder and Body are all brand new and both battery test lights glow red ok.

When I load the film and close the back etc and move the power winder switch to start, the film advances to frame one ok I make sure that the switch under the power winder is not set to multi. I then remove the dark slide, set the aperture and shutter speed align shutter release button the white dots and fire the shutter, all is well, the power winder advances the film ok and I can repeat the firing however, after about 6-8 shots the shutter stops firing. All I can do to get the shutter to fire is turn the shutter release button to the yellow dot and it then fires, I then seem to be able to return the button to white and fire the next few shots then the shutter fails again. This also occurs when I have no film in the film back.

Has anyone experienced this, are there any tests I can do, I don’t have a hand crank but I do have a remote shutter release on order.

I’ve noticed there are four little electrical contact on the film back that mate with the rear of the body what are they for. Also just to note the back fits nice and snug on the body.

Any help / comments greatly received.

Thanks

Chris

 

[MattKing]

Chris:

This won't help you with your problem. The electrical contacts on the film backs communicate the ISO setting that you set on the dial on the back. This tells the metered prisms (if you have one) what they need to know in order to provide a meter reading.