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Message |
    
Hobbes
Tinkerer
Username: Hobbes
Post Number: 12
Registered: 02-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, November 16, 2010 - 08:14 am: | 
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I have a double stroke M3 that is giving me some problems when I attempt to fire the shutter.
When I use color film or slides the button more often than not refuses to move and trigger the shutter. In order to push the button down enough, I have to slightly put pressure on the film advance lever while pushing down on the shutter button.
At first this problem did not occur with black and white film. Now it is increasingly happening with B/W film.
I never get the problem when firing the shutter when there is no film in the camera.
Has anyone ever encountered a problem like this before? If so, is it an easy fix?
Thanks,
Rob |
T6nn
Tinkerer
Username: T6nn
Post Number: 5
Registered: 06-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, November 16, 2010 - 10:39 am: |
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See here: http://www.pentax-manuals.com/manuals/service/leica_m2_service.pdf
The first two lines in the troubleshooting section seem to adress your problem. I think you need to adjust the "release disk"
above the take-up spool. But be careful as the manual is for a later leica with a fixed take-up spool. |
Glenn
Tinkerer
Username: Glenn
Post Number: 864
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, November 16, 2010 - 03:03 pm: |
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If you are absolutely sure that the shutter releases 100% with no film in, the problem could be due to the resistance of film in the gate/pressure plate or cassette stopping the shutter fully cocking. This certainly can occur in a double stroke M3 that is worn/in need of adjustment. Your statement that the thinner B/W emulsion films did not initially cause this problem would seem to verify this probable cause. You should also make sure that the back of the camera has not been dinted/distorted and that the rewind knob mechanism is completely free to rotate.
If you are prepared to sacrifice a few inches of film, the following 'test' can be quite revealing - Load a cassette of film and try to advance some frames through the camera (5/6 should be enough). Now open the camera and cut off the advanced portion of film, then reload the camera with this small length of film, placing the roll loosely in the cassette space. If the reloaded length can be advanced and the shutter released normally, the fault is in the rewind knob or friction in the cassette spool caused by the location points for the cassette. If the shutter still does not release with this short length of film in place, then you should check the feed of film through the gate/pressure plate interface.
Only after eliminating film feed problems should you start to dive into this camera. Don't forget to re-trim the end of the film remaining in the cassette! |
Hobbes
Tinkerer
Username: Hobbes
Post Number: 13
Registered: 02-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, November 16, 2010 - 06:28 pm: |
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Thanks, T6nn and Glenn, for your responses.
I tried Glenn's test with some loose length of color film. The shutter still won't fire even if the film is loose in the cassette chamber.
When I keep the back door open when I advance the film, the camera fires properly. If I keep the back door open and put my finger on the film (so as to cause tension on the take up roller) as I advance the film, the camera does not fire the next time I push the shutter button. So it looks like either the film pressure plate or the two little bumps on the back door near the sprocket are pushing down too hard on the film. (The back of the camera looks like it is not dented or distorted.)
Is there an easy way to relieve some of the pressure on the film as it advances?
Thanks again.
Rob |
T6nn
Tinkerer
Username: T6nn
Post Number: 7
Registered: 06-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, November 17, 2010 - 10:12 am: |
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Well, neither the the pressure plate or the "bumps" don't press the film tightly against any other part of the camera. The friction is there only due to film's elasticity (and it needs to be there). It's normal that film tries to pull gears backwards after the wind stroke, and that gears do have a play and allow that.
But leica also has a blocking mechanism to prevent you from depressing the shutter when it's half-wound. The "release disk" has a slot in it that needs to be lined up with a rod under the shutter button, in order to unlock the release. I can't see it on my m4 with it's unremovable take-up spool, but you should be able to observe it. At least you could test the release without the film while you wiggle slightly the take-up spool by hand- if you can block the release, you have diagnosed the fault.
But as for the disassembly and adjustment- I hope someone with better knowledge about m3 will join the discussion. |
Hobbes
Tinkerer
Username: Hobbes
Post Number: 14
Registered: 02-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, November 17, 2010 - 12:18 pm: |
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T6nn describes the situation well. After replicating the problem, I have removed the film and the take up spool and can see that the notch in the release disc does not quite line up with the rod under the shutter button.
When I poke at the release disc with a dental probe, I can see a little play in it. |
Glenn
Tinkerer
Username: Glenn
Post Number: 865
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, November 17, 2010 - 01:40 pm: |
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Unfortunately, as I intimated in my first paragraph, your M3 seems to be exhibiting a classic case of excessive wear preventing the 'wind on' completing its full cycle. My personal advice is to find a good Leica technician and get it properly serviced and rebuilt - These cameras were assembled with parts hand picked for minimum working tolerances, so wear caused by lack of frequent and proper servicing will soon turn the early M Series into expensive paper weights.
Do not try the ultimate DIY butchery - filing the notch out to clear the 'rod'. Have seen a couple of cosmetically mint M3's with this delightful mod! No need to state in which Bay they were found - fortunately there is a very good Leica restoration company here in the UK. |
T6nn
Tinkerer
Username: T6nn
Post Number: 9
Registered: 06-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, November 17, 2010 - 04:33 pm: |
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Glenn is right - This malfunction may indicate worn gears, so it may be ultimate time for a proper CLA. |
Hobbes
Tinkerer
Username: Hobbes
Post Number: 15
Registered: 02-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, November 17, 2010 - 05:38 pm: |
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Thanks for all the input. I guess it's off to the repair shop. |
