Pentax 6x7 mirror stuck halfway

[mlu19]

Hi,

I just got a Pentax 6x7 MLU body w/ 105 lens. While testing the camera, I ran into my first problem. I've searched on the net for a couple days and also reached out to Eric from pentaxs.com for the problem. He replied that he's never seen this problem before.

Here is the problem: all shutter speeds works, including bulb mode. However, at speed 1/30th and 1/60th only, the mirror would lock up right in the middle after firing the shutter. Pressing the reset button would bring the mirror up and then I was able to fire the shutter again to bring the mirror down to its starting position. I've tried switching to a new Duracell 28L battery; it didn't help. All other speeds, including slower speeds at 1/15, 1/8, 1/4, 1/2, and 1 work and sound right.

Has anyone ran into the same problem and possibly have a fix for it?


Many thanks,
Mark

 

[Fixcinater]

One of my non-MLU bodies got stuck halfway up, but it won't cycle at all.

So...I'm of no help.

 

[Poisson Du Jour]

The process you described sounds like a lazy / sticky mirror activation solenoid (another also exists for the shutter but separately), assuming the battery is fresh and not in a state of depletion (which is where the mirror reset button procedure is taken up, and that you have tried without success). The other problem could be the rudimentary resistors that govern the shutter speeds of 1/30 and 1/60th, especially since it appears the fault is not repeating at any other speeds. It's worth noting that that leaving the shutter dial on any speed for a prolonged period of time will make the speeds inaccurate (when not in use or in storage, the dial should be set to B or X). The older 6x7 bodies do need to be serviced after so many decades of use and the resistors, mirror/shutter solenoids and winding mechanisms are commonly cited for servicing work.

 

[mlu19]

So..the mirror magically worked this morning at all speeds. I've been taking the lens and TTL prism on/off to dry fire the body. It still boggles my mind that I had the same problem for 2 days and now it magically went away. Could the manual/auto tab on the lens be the cause? Thank you, Fixcinater/Gary for your responses!

 

[Poisson Du Jour]

Well, a bit of good news after all — and hoping it stays like that. Just a by-note: observe the correct procedure for reducing the risk of stress on the meter coupling chain: if you have a lens attached to the camera and you remove the prism, remove the lens and then re-attach the prism, in that order. Any other method literally screws the rudimentary coupling that can actually snap the chain, resulting in a somewhat expensive (and intricate) repair job. In all honesty though I don't see how this could affect the position of the mirror, but everything has to be considered with the Pentax 6x7 and 67 bodies!

 

[Hatchetman]

I had a suspicion it may have something to do with the lens auto stopdown mechanism. I have one lens that makes my 6x7 act funny. mirror locks up when I put it on. Don't know what's going on.