Mamiya 80mm lens fires flash while cocking the shutter

[miha]

As the title says, the Mamiya-Sekor 80mm f2.8 (belonging to my C330 camera) fires the flash also while cocking the shutter. So every time I intend to use the flash I need to switch it off before I cock the shutter. Is this a common problem with these old Seiko shutters and more importantly is there a quick solution to this problem, like minor lens disassembly?

 

[grahamp]

It is not a common problem. The sync setting is X? Does the flash discharge when the shutter is cocked, or un-cocked, or just when you cock it? Does it happen at slow and fast speeds?

Does the flash behave normally on a different camera or shutter? Can you try a different sync cord?

It sounds like there is something shorting the connection while the internals move. You should be able to cock the shutter with a charged flash without any problems.

It could be that the wire (there is only one - the return on the circuit is via the metal of the shutter) is not properly soldered and moves when the shutter is cocked.

I'd start with the sync cord, then the sync socket on the shutter, and only then consider opening up the shutter.

 

[miha]

It is not a common problem. The sync setting is X? Does the flash discharge when the shutter is cocked, or un-cocked, or just when you cock it? Does it happen at slow and fast speeds?

Yes, the sync setting is X. It fires on both occasions.

Does the flash behave normally on a different camera or shutter? Can you try a different sync cord?

Yes, it does, on numerous different cameras. It's a Metz 45 flash with its dedicated cord, I have no extra cord available, but it's not the cord causing this.

It sounds like there is something shorting the connection while the internals move. You should be able to cock the shutter with a charged flash without any problems.

Indeed.

It could be that the wire (there is only one - the return on the circuit is via the metal of the shutter) is not properly soldered and moves when the shutter is cocked.

I'd start with the sync cord, then the sync socket on the shutter, and only then consider opening up the shutter.

Thanks.

 

[BrianShaw]

If there are no other preexisting problems, the solution is likely a routine shutter overhaul, or as the forums like to call it… CLA. The shutter’s synch mechanism, or a related lever/spring, is likely sticking and prohibiting proper spring action to prevent electrical contact when such contact is not intended.

Probably neither a common or uncommon problem… just a problem that should be easily resolved. Only you can say if it’s DIY or not.