Mamiya M645 1000s shutter sticks at 250 and 500

[scanalog]

Hi there, my camera's shutter has been sticking lately, but only at 250 and 500 shutter speed. I have fresh battery in there, and it lights up green when I press the battery test. I've read some other threads where people say that if you fire the camera with no film and it's not on multi, you can mess up the shutter. Could that be the culprit? If so, why only at those speeds? For a while it was just at 500. Now it's also at 250. Is there a fix or is it just aging and getting ready to be FUBAR?

 

[Oldwino]

Mine did that and shortly afterwards, the shutter completely went south. Turns out there's a capacitor in the timing circuit that goes bad (after all these years). I ended up having the camera fixed, and CLA'd too, as I figured if I buy another one, for about the same price, this problem is probably going to happen again. So now I have a "new" camera that works great.

 

[reddesert]

I don't think you can damage the camera by firing it with no film and not on multi-exposure; that sounds like someone was confused. With the camera not on multi and no film loaded, once the shutter is fired, you can turn the wind knob freely and it will not stop, or cock the shutter. But that's how it's supposed to work. One needs to put it on multi to test fire it without film. Or use a roll of backing paper instead of film.

The shutter is electronically timed, so if it fails at the highest speeds but works ok at the slower speeds, that may suggest a electrical problem rather than mechanical.