Pentax 6x7 top two speeds not working right

[mweintraub]

Another one of those "is it hard to fix" question.

My Pentax 6x7 isn't working right at 1/1000s and 1/500s. 1/1000s is pretty much blank and 1/500s, you'll see a dark side (1/3-1/4 of the frame). I used a binder clip to fake the camera to think the back is closed and I didn't see the shutter open much (if at all) at 1/1000s. At 1/500s I did notice it open, but could tell it's not moving right.

I have a chance to buy a new body for $230. But I was thinking of fixing it myself or get it fixed. I've read and seen photos about problems with the shutter speed dial, would this be the cause? Thoughts?

 

[shutterfinger]

With the back open release the shutter on B- 1st curtain should open and the image frame should be clear of any obstructions. Release the shutter release and the second curtain should close in a smooth fashion. Pay attention to the lead edge it should stay perpendicular to the image opening as it crosses the image opening, if it does not there is possibly debris in the shutter track or the lubrication is dry. If the shutter is smooth with no bends or bows in opening or closing then the electronic release is at fault. Have it serviced.

 

[Poisson Du Jour]

If it is an old Asahi-Pentax 6x7 then the chances are it is an age-related fault, and as you've commented, there are known problems with the shutter speed dial that can be related to the ingress of dirt, moisture or simply normal wear and tear over a long period of time — and the greater bulk of these 6x7s are now pushing toward 50 years, a lot without ever seeing a service bench. Apart from broken aperture coupling chains, loss of accuracy of shutter speeds is probably the second most common development iin time. (By way of mention, the shutter speed dial should be turned to either B or T when the camera is not in use for an extended period of time.)

The Pentax 6x7 / 67 Engineering Manual is an interesting read for the complexity and precision of the camera's assembly (particularly the shutter, mirror and shutter speed governor assembly). But it's definitely not a camera I would pull apart in my spare time.

 

[mweintraub]

With the back open release the shutter on B- 1st curtain should open and the image frame should be clear of any obstructions. Release the shutter release and the second curtain should close in a smooth fashion. Pay attention to the lead edge it should stay perpendicular to the image opening as it crosses the image opening, if it does not there is possibly debris in the shutter track or the lubrication is dry. If the shutter is smooth with no bends
or bows in opening or closing then the electronic release is at fault. Have it serviced.

I'll try that tonight. Thanks. I'm sure people here at work don't want to hear the lovely music the P6x7 makes.

If it is an old Asahi-Pentax 6x7 then the chances are it is an age-related fault, and as you've commented, there are known problems with the shutter speed dial that can be related to the ingress of dirt, moisture or simply normal wear and tear over a long period of time — and the greater bulk of these 6x7s are now pushing toward 50 years, a lot without ever seeing a service bench. Apart from broken aperture coupling chains, loss of accuracy of shutter speeds is probably the second most common development iin time. (By way of mention, the shutter speed dial should be turned to either B or T when the camera is not in use for an extended period of time.)

The Pentax 6x7 / 67 Engineering Manual is an interesting read for the complexity and precision of the camera's assembly (particularly the shutter, mirror and shutter speed governor assembly). But it's definitely not a camera I would pull apart in my spare time.

Yeah, I think I have a really early model. Debating on doing a full CLA or buying a replacement 67. =/

How's an "extended period of time"?

 

[shutterfinger]

12 hours or longer.

 

[mweintraub]

12 hours or longer.

Ouch! Really?!


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[Poisson Du Jour]

12 hours or longer.

Six to 12 months.

There is no harm to either the 6x7 or later 67 bodies if the shutter speed is left there for a couple of weeks, but good habits should be started early. There are many cameras that see no action for months and this is not how they should be used. Using them regularly is better than mothballing them with nothing to do.
I think you should go for the 67 bodies; there are still very good specimens out there and a lot of engineering improvements were made in those bodies coming out in 1991-1992 (more robust aperture coupling chain is one of them).