[montecarlo]

Hello,

I've ecountered some problems with my MX. Its shutter is stuck in cocked position (the indicator near the shutter button is red). Mirror is down and I can push the shutter button all way down and nothing happens and can not wind of course.

In the attachment is the MX without the botton cover.

BTW, how can I take down the top cover?, especially how to dismantle de shutter times dial (at what should I care more, are there some setttings I should remeber, before dismtle the dial? etc?)

Thank you very much.

Attached Images

 

[wtlwdwgn]

I can't help with any disassembly but Eric has done wonders with my film bodies.

[vladimiroltean]

This is how a working MX bottom should look like. Pardon the large image, but it's in the interest of better sight

Also be sure to read this: Jammed Spotmatic. Sure, not the same camera, but it may help nevertheless.
To get the top cover off, you need a pointed tip lens spanner.

[MysteryOnion]

To see better, you should get under the low speed assembly.

So... in your image I marked where you should look...



The screw head with a roller sleeve as circled, an arm is supposed to push it to the reset position. With the low speed assembly out of the way, you'll have good look at it.

[LMX]

Hi everyone,
I know it's an old thread but I'm facing the similar problem. I have advanced the frame, but shutter is stuck in (almost) cocked position, red indicator is not showing in the window and is somewhere in between. I've checked the service manual but cant figure out where to look. It was fully functional camera with a dent on prism area.
I swapped the top cover from a clunker and it was all ok. only during testing advance lever retainer cap became undone and I kinda advance it when it was a little wobbly. that's where all got jammed. any idea is welcome. thanks.

[m_rabiller]

To see better, you should get under the low speed assembly.

So... in your image I marked where you should look...



The screw head with a roller sleeve as circled, an arm is supposed to push it to the reset position. With the low speed assembly out of the way, you'll have good look at it.

Thanks for the tip. I recently got a jammed MX I ordered for its focussing screen. Obviously wanted to try to get it unstuck anyways. I removed the slow speed assembly as you showed, and try to get the various bits to move. at some point I realized with a bit of pressure, the post you circled in green would move back and forth, but the camera was still stuck. I then pocked a bit around carefully without noticeable effect, and was about to quit when all of a sudden there was a kind of "clack" sound, and the film advance was all right. Curtain was still kind of lazy, and the mirror kept getting stuck (you can free it with that lever on the right of the mirror box). Hummm... was getting late, let's see another day. A few days later, sthe curtain didn't seem so lazy but the mirror was still getting stuck. And this morning, wow... everything is behaving just fine. Magics... you get to love these Pentax

[marcelezaaa]

I just got an used Pentax in very good condition but was displaying the same behavior as the OP. I got it working via the following steps. I hope it helps.

Issue description:
- shutter button can be pressed but nothing happens as if after taking a picture and before winding.
- stuck winder: it can open slightly (as one would in order to keep the light meter on) but would not move past that.
- the red/orange dot in the top plate would sign that the camera is cocked.

Steps:
1) disassembly slow shutter mechanism (already taken off in the first image, but screws holes are marked in green)
-> maybe one could do it with the slow shutter mechanism still in place, if you know exactly what you aree
2) move piece marked in red towards lens mount. It is held by a strong spring, so you can expect some resistancy.
3) assembly slow shutter mechanism back
1) it is fiddly, it seems that only one part sits properly (upper right) and other part (lower left) sits slightly loose before screwing it in (if you press down at the lowerleft, the upper right part will raise). Maybe it is supposed to be like that (to be easier to remove and put it back)
4) in my case, after putting the slow mechanism back together (still in Bulb mode), the mechanism did not engage straight away (it would shutter at some faster speed).
1) I slowly changed the speed all the way to 1s/1000, and slowly changed back to B and this time it got engaged.

So far all speeds are working fine and they seem plausibly correct. I hope it helps.

Attached Images

 

[Benz3ne]

So my MX has shown a similar problem. I thought I'd finished a roll of film. I can actuate the sprung 'reset screw' that has been mentioned above without removing the slow shutter assembly, but when I fire then rewind the film advance lever, that 'reset screw' then falls back where it shouldn't, so the shutter won't fire again.
Thoughts?

[grimnicholas]

I just got an used Pentax in very good condition but was displaying the same behavior as the OP. I got it working via the following steps. I hope it helps.

Issue description:
- shutter button can be pressed but nothing happens as if after taking a picture and before winding.
- stuck winder: it can open slightly (as one would in order to keep the light meter on) but would not move past that.
- the red/orange dot in the top plate would sign that the camera is cocked.

Steps:
1) disassembly slow shutter mechanism (already taken off in the first image, but screws holes are marked in green)
-> maybe one could do it with the slow shutter mechanism still in place, if you know exactly what you aree
2) move piece marked in red towards lens mount. It is held by a strong spring, so you can expect some resistancy.
3) assembly slow shutter mechanism back
1) it is fiddly, it seems that only one part sits properly (upper right) and other part (lower left) sits slightly loose before screwing it in (if you press down at the lowerleft, the upper right part will raise). Maybe it is supposed to be like that (to be easier to remove and put it back)
4) in my case, after putting the slow mechanism back together (still in Bulb mode), the mechanism did not engage straight away (it would shutter at some faster speed).
1) I slowly changed the speed all the way to 1s/1000, and slowly changed back to B and this time it got engaged.

So far all speeds are working fine and they seem plausibly correct. I hope it helps.

Hi! Super helpful. I removed the slow speed and cleaned / re-lubed things and it’s all going well as far as the mirror moving.
However, now I’ve noticed that all speeds work well except 1/8th which seems to shoot at maybe 1/125th. Sort of like the slow speed mech hasn’t been engaged at all for that speed.
Could that indicate it wasn’t reinstalled properly or something else?
Hmmm

EDIT// speeds all correct. I looses both screws on the slow speed gear and prioritised tightening the top right (closes to lense) screw and it all has synced up.
So far so good

[Benz3ne]

Hi! Super helpful. I removed the slow speed and cleaned / re-lubed things and it’s all going well as far as the mirror moving.
However, now I’ve noticed that all speeds work well except 1/8th which seems to shoot at maybe 1/125th. Sort of like the slow speed mech hasn’t been engaged at all for that speed.
Could that indicate it wasn’t reinstalled properly or something else?
Hmmm

I found that scrolling it through to bulb mode 'clicked' everything back into place with regards to the slow shutter mechanism. Might not work for you but could be worth a go?

[grimnicholas]

I found that scrolling it through to bulb mode 'clicked' everything back into place with regards to the slow shutter mechanism. Might not work for you but could be worth a go?

Thanks! I figured out it was slightly slightly uneven on the re-screwing and fixing of the timing gears. I tweaked that and all working

[WOJE]

So my MX has shown a similar problem. I thought I'd finished a roll of film. I can actuate the sprung 'reset screw' that has been mentioned above without removing the slow shutter assembly, but when I fire then rewind the film advance lever, that 'reset screw' then falls back where it shouldn't, so the shutter won't fire again.
Thoughts?

Did you manage to find a solution? I'm experiencing this exact problem right now

[vandergus]

I can give some more explanation but I'm still don't know a good solution outside of swapping parts.



Here's a picture of what's going on under (above?) the bottom plate, on the bottom of the mirror box. The red arrow is pointing to the post that gets pushed up when the camera is wound. It is supposed to charge the large coil spring on the left. When it is pushed to the proper height, the latch (blue arrow) swings over and keeps it from falling back down. Sometimes the latch doesn't latch. It's either sticky from grime or the post simply isn't pushed high enough anymore. It's usually the latter and I honestly don't know a good way to fix it. There are no adjustment points for this mechanism, no way to tune the engagement. It is just as built. And all of the components are made of hardened steel, which are not receptive to bending or hand filing. My next attempt would be removing material from the notch with a small rotary grinder (aka Dremel), but it does seem a bit extreme. I fixed the last camera by replacing the latch with a part from another camera.

One more note on the slow speed mechanism. I would avoid removing it unless you have a way to measure the shutter speeds. The slow speeds are set by tuning the overlap between two catches (green arrow). When you reinstall the governor, there is enough play in the screw holes (yellow arrows) to significantly change this overlap. You almost never get it back in the same way it came out. So after reinstalling the mechanism, you need to be able to check the speeds and adjust them to the correct timing.

[Benz3ne]

Did you manage to find a solution? I'm experiencing this exact problem right now

I’d found the offending “latch” but couldn’t go past that. Ended up sending it for a repair. Works perfectly now.

[WOJE]

I can give some more explanation but I'm still don't know a good solution outside of swapping parts.



Here's a picture of what's going on under (above?) the bottom plate, on the bottom of the mirror box. The red arrow is pointing to the post that gets pushed up when the camera is wound. It is supposed to charge the large coil spring on the left. When it is pushed to the proper height, the latch (blue arrow) swings over and keeps it from falling back down. Sometimes the latch doesn't latch. It's either sticky from grime or the post simply isn't pushed high enough anymore. It's usually the latter and I honestly don't know a good way to fix it. There are no adjustment points for this mechanism, no way to tune the engagement. It is just as built. And all of the components are made of hardened steel, which are not receptive to bending or hand filing. My next attempt would be removing material from the notch with a small rotary grinder (aka Dremel), but it does seem a bit extreme. I fixed the last camera by replacing the latch with a part from another camera.

One more note on the slow speed mechanism. I would avoid removing it unless you have a way to measure the shutter speeds. The slow speeds are set by tuning the overlap between two catches (green arrow). When you reinstall the governor, there is enough play in the screw holes (yellow arrows) to significantly change this overlap. You almost never get it back in the same way it came out. So after reinstalling the mechanism, you need to be able to check the speeds and adjust them to the correct timing.

Thank you for taking the time to reply, I was away on holiday and didn't notice. I tried replacing the light seals on the camera and used alcohol to remove the old ones, it seems like they melted into the mechanism and jammed it somehow.

I unfortunately already removed the slow shutter assembly before I saw your warning, im currently able to push the post into position and trigger the shutter, but only manually. I guess the problem lies with the mechanism pushing the pin about 2mm less than it should and not with the catch lever. Unless you would be able to provide any ideas, I'm don't think I'm comfortable disassembling further so I'll see what the repair shop can do.