Stuck shutter - Schneider Xenar 150/4.5 / compur

Help!

 

Just pulled out my MPP Microtechnical to show it off to someone, cocked the shutter to put it in ‘t’ so they could look through it and go ‘oooh’, and the shutter won’t fire? It doesn’t want to go into bulb or timed, or into the fastest speed ( an eye watering 1/400th). Aperture is fine and functional. Can anyone help? Do I need to ‘go in’ and if so, is it difficult or unadvisable. Thanks in advance

I don't know your camera at all, but if you can expose the shutter mechanism, this may be a place where the tiniest drop imaginable of naphtha could loosen up dried lubricants combined with working or trying to work the mechanism.

Seriously, just what can be held on the point of a needle, then redo if necessary. Never flood anything with any solvent.

Which Compur? I know of at least 6 different variations over time.

 

Does it have a 'preview' lever, or do you have to pull a small button back while firing to get the shutter to stay open?

 

Putting the shutter into the fastest speed after cocking isn't a good idea IMO. It engages an extra spring and at best requires quite a bit of extra force on the selector ring.

 

It sounds like the shutter is just sticky. A gentle push on the cocking lever while holding the release down may persuade it to fire. After that it may release properly, and a few additional firings might clear any issue altogether.

 

Failing that, it probably needs a strip down and clean/lube. Access is got by removing the front plate, but the exact procedure depends on the vintage of the shutter.

Sorry, I meant to upload a photo! Thanks for advice so far, will give that a go

 

Which Compur? I know of at least 6 different variations over time.

 

Does it have a 'preview' lever, or do you have to pull a small button back while firing to get the shutter to stay open?

 

Putting the shutter into the fastest speed after cocking isn't a good idea IMO. It engages an extra spring and at best requires quite a bit of extra force on the selector ring.

 

It sounds like the shutter is just sticky. A gentle push on the cocking lever while holding the release down may persuade it to fire. After that it may release properly, and a few additional firings might clear any issue altogether.

 

Failing that, it probably needs a strip down and clean/lube. Access is got by removing the front plate, but the exact procedure depends on the vintage of the shutter.

 

Thanks for the advice

Sadly, that didn’t work. Previous picture shows lens and shutter, I think it dates from about 1953.

OK. I would have guessed it was 1950s from the 1/400th top speed.

 

Dismantling to the point of exposing the 'works' is reasonably easy.

 

1. Remove the front half of the lens.

2. Locate a two-hole screw alongside a scalloped collar.

3. Rotate the screw until it clears the scallops.

4. Mark the position of the brass collar.

5. Unscrew the brass collar.

6. Carefully remove the front plate of the shutter. (There may be a stray spring underneath, so lift the plate slowly and carefully).

 

The whole of the shutter gear train should now be exposed, and can be cleaned, lubed and adjusted if necessary. The CLA procedure is a little beyond quick explanation here.

OK. I would have guessed it was 1950s from the 1/400th top speed.

 

Dismantling to the point of exposing the 'works' is reasonably easy.

 

1. Remove the front half of the lens.

2. Locate a two-hole screw alongside a scalloped collar.

3. Rotate the screw until it clears the scallops.

4. Mark the position of the brass collar.

5. Unscrew the brass collar.

6. Carefully remove the front plate of the shutter. (There may be a stray spring underneath, so lift the plate slowly and carefully).

 

The whole of the shutter gear train should now be exposed, and can be cleaned, lubed and adjusted if necessary. The CLA procedure is a little beyond quick explanation here.

Thanks very much for that, I have some very limited experience of lens dismantling, such that 'reasonably easy' should be within my grasp. I'll give it a go.

i just overhauled an older compur #1, max speed 1/125th on a zeiss maximar that sat in a closet since the begining of time. the old lube was extreamly dried out n oil was all gone. like yours it just refused to move.

 

compurs are very finicky shutters and do require the proper lubes. for a non invasive treatment, try putting it in the sun or heating it gently. if it does start to run, give it a good work out to keep it moving. thats worked for many temporary jump starts.

 

my sugestion is have it serviced, not a diy project unless you are reasonably familir with shutter repairs, especially compurs. they do get tricky. a good cla will give that shutter a good 30 years of reliable service.

 

the saying goes... if it turns, oil it. if it rubs, grease it. but use caution with lubes... the smallest amount is all it needs. the thinnest smear is more than enough.

Eek, it’s ‘orrible in there!

 

So I’ve had some time to get inside the lens now, and through a process of very gentle prodding here and there, have deduced that there is a lever, that needs to swing out the way during the shutter cocking process, in order to make the shutter release operative. You can see both on the attached photo. (Excuse child-like drawing, PC u/s at the moment so done on iPad.) I have managed to free up the shutter, but that lever will not swing out of the way to give clearance to the shutter release. I can move it out the way with a cocktail stick, and then the shutter will fire, but I assume it should be connected somehow to the cocking mechanism, so that it moves out the way when you cock the shutter automatically?

Might it have something to do with that ‘ big’ on end spring at 2 o’clock? That is quite loose and the free end can rotate through about 45 degrees?

 

Update. I seem to have freed up the lever, so it will now fire the shutter. I have a new problem, in that the shutter won’t fully engage. I can move it to almost the point at where it catches, but it won’t catch. It will work in self timer mode, but again, it won’t actually catch. There Is a lever (1) which should engage in notches (2) to hold the shutter cocked, but this appears to have lost it’s sprung-loadedness?

Oops, here’s the photo

 

Update. The little wire 'spring' shown at the head and above of arrow 1, has a free end. Looks to be part of the mechanism that moves lever into the notches (2). There is a free hole (just to RHS of arrow head 1) that looks like it might be where the free end goes, but it is a bit of a stretch, and I am loath to pull it there in fear of bending it. Also, I can't see what it might do even if I do locate it there. Seems there should be something to spring the lever automatically into the notches, which is freed by the shutter release.

 

Any help very gratefully received!

Is the loose spring you're talking about the long blued-steel tension spring just to the left of the red 'Lever' arrow?

 

It has two looped ends? I believe the loose end should hook over the notched protrusion on the arrowed lever. The fixing point is partially obscured by a round-ended lever.

 

A bit late to mention it now, but operating the shutter with the top-plate off isn't a good idea. Removing the top-plate should be an exploratory move to see if anything is broken, or to clean and lube the gear trains (if necessary).

 

As you've discovered, things can easily pop out of place without the restraint of the front cover.

 

BTW, the thin hairspring wrapped around the pivot should also hook over the lever next to it I believe.

Is the loose spring you're talking about the long blued-steel tension spring just to the left of the red 'Lever' arrow?

 

It has two looped ends? I believe the loose end should hook over the notched protrusion on the arrowed lever. The fixing point is partially obscured by a round-ended lever.

 

A bit late to mention it now, but operating the shutter with the top-plate off isn't a good idea. Removing the top-plate should be an exploratory move to see if anything is broken, or to clean and lube the gear trains (if necessary).

 

As you've discovered, things can easily pop out of place without the restraint of the front cover.

 

BTW, the thin hairspring wrapped around the pivot should also hook over the lever next to it I believe.

Thanks for your input, I appreciate it. The spring referred to is just a bit of bent wire, see blown up version of the photo. You can see a free end, pointing away from the viewer, exactly at the point of the lower yellow arrow. Should this free end connect to something, or be anchored somewhere? It’s well hidden if it should be. There is a hole at 5 o’clock from the end of the wire, which could be the culprit, but it seems a long stretch. The lever that sits under the end of the lower arrow is the one that engages with the notches in cocking ring, and which doesn’t appear to function properly.

 

Edited June 1, 2018 by stuart_pratt

With the help of a french online repair manual, I think I've got all the parts back in the right place. The shutter still fails to cock, unless you leave it a while, during which time you can just about hear a very, very faint sound of whirring gears, almost as if something hasn't quite unwound enough to enable the shutter to re-cock.Once it has 'unwound' it seems to function OK. Any ideas anyone??

The manual is here: Compur shutter repair manual

Ignore that. It's the hard drive of my PC clicking!!

Suggest you replace the top plate and gently screw the retaining nut in place. You might need to partly move the cocking lever while positioning the plate, and 'jiggle' the whole mechanism to make sure everything is settled into place.

 

The retaining nut shouldn't be screwed down tight. Doing so will bind the mechanism. You need to align the appropriate cutout with the locking screw-head that prevents it turning.

 

Hopefully the shutter will work correctly once everything is held in place by the cover plate.

I think I’ll do that. It does seem to work, only intermittently. If it takes some time to ‘settle down’ it might have been like that for some time - how often do you fire the shutter of a LF camera in quick succession? I’m sure I’m almost there, like you say, it might need the comfort of the top plate to keep it all in exactly the correct position. Thanks for input.

OK, so I'm SLOWLY getting to grips with what bits serve what functions, and I have come to the conclusion that in order to fully cock, (i.e engage that final 'click' that stops the shutter firing) the mechanism shown on the RHS of the attached drawing needs to somehow engage with the mechanism above it (and shown on LHS) and the lever 'A' then rotates in a clockwise direction, and the point of it, ratchets into the notches to stop the shutter uncocking. This is only happening intermittently, even when face plate is on. It's very difficult to see how the buried mechanism works, 'cos its buried!. I'm not even thinking of taking the RHS off to get at it, in fear that I'll lose something, or it won't go back together in the way it came off. I'm still not sure I have the hairspring in the correct spot, but it gets dragged along clockwise as you tension the shutter, and engages with the notches as shutter is fired.

 

Considering the 'flood with naptha' option, on the assumption that something in the lower mechanism is gummed up. I'd only do it in a shallow bath, and just on the bit that needs it, not elsewhere.

Also, the preview lever, won't stay held in the open position - I can live with that by using 'T' and wide open, but wonder if it might be a symptom of the same issue?

 

Edited June 4, 2018 by stuart_pratt

Why not just let a camera repair shop fix it correctly before you must have one do a repair from your tinkering?

Why not just let a camera repair shop fix it correctly before you must have one do a repair from your tinkering?

I'm cheap!

 

It's an option, sure. But I feel like I'm so close, and I'm learning something. The original problem was that it was stuck cocked. That seems to have been resolved, but I have another problem, probably to do with something I have inadvertently 'amended'. Of course, I could go along like this ad infinitum, so yes, I am seriously also considering quitting while I am ahead.

Have you hooked the red-arrowed hairspring (as seen in line drawing) back over the lever beneath it?

 

Your photos show that it was misplaced. It shouldn't catch on the rotating ring at all.

 

Do not flood with naptha! That should never be needed. Even if the shutter blades have been stuck with oil, flooding them with solvent only provides a temporary fix.

 

I presume your shutter doesn't have stuck blades, and the gear train pivots look clean and dirt free. I suspect the only thing wrong now is that something is misplaced.

 

Re-check the actual position of all parts against what's shown in the line drawing. And put the Naptha away!

Have you hooked the red-arrowed hairspring (as seen in line drawing) back over the lever beneath it?

 

Your photos show that it was misplaced. It shouldn't catch on the rotating ring at all.

 

Do not flood with naptha! !

OK, naptha gone!

 

Yes, the hair spring is now in the correct place, or at least close to the correct place. In the close up photo, it is to the RHS of the trunnion above it, which was incorrect, it should be to the LHS. When I found that error, I thought 'that's it!' Oh well. You say the end of the hairspring shouldn't catch on the rotating ring at all, but I have a view in the manual which shows it's correct location when the shutter is tensioned for the self timer, and normally, and it looks as if it sits close the 'grooves', see below?. Is it not supposed to move with the ring when the shutter is cocked and released? Oh, maybe the bent free end of it is just to prevent the lever from extending too much in an anti-clockwise direction? Its orientation in the two diagrams below looks the same, regardless of shutter tension.

 

Thanks for continued advice.

 

 

 

I'm cheap!

 

It's an option, sure. But I feel like I'm so close, and I'm learning something. The original problem was that it was stuck cocked. That seems to have been resolved, but I have another problem, probably to do with something I have inadvertently 'amended'. Of course, I could go along like this ad infinitum, so yes, I am seriously also considering quitting while I am ahead.

If you are “cheap” then you are creating a more expensive repair!

If you are “cheap” then you are creating a more expensive repair!

Quite possibly, but ill advised or not, its a chance I'm willing to take.