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11-15-2020, 07:15 AM   #1
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Pentax LX calibration issue?

Hi all

About 2 years ago, I got into collecting film SLRs made by the - back then - "Big Five" and have since then acquired quite a collection of Canon, Minolta, Nikon bodies and started to complement those by a (slowly) growing number of Olympus and Pentax bodies.For day-to-day photography, I tend to use one of my Canon DSLRs (77D, 5D Mk. IV) and for "experiments" with old MF lenses I have a little M100 in my arsenal which is - being mirrorless - really nice for adapting all this old glas But from time to time - as far as all the other "chores" allow it - I like to be out in the field with an old-fashioned film SLR, shooting nature and wildlife. So my ambition is to have all the SLR bodies in my collection in reasonable working order...

Recently, I acquired a bundle of Pentax gear that also included an (alleged working) LX. Upon closer inspection, it turned out that it suffered from the well-known - and in this case rather severe - "Sticky Mirror Syndrome", meaning that all three polymer pads (mirror rest left & right + diaphragm actuator dampers ) had decayed into a gooey mess. The mirror light seals have also been in a rather bad shape, i.e. gone "flaky" and slightly sticky. But after carefully cleaning out the debris, it still has a peculiar issue with the mirror - or rather the first shutter curtain:

- If the mirror is locked up via the MLU lever, it works like a charm and timing appears to be reasonable. Whether it actually *is* accurate, I have to check with my newly arrived shutter tester.

- When leaving the mirror in its "default" position, firing the shutter will flip up the mirror but not trigger the shutter curtain(s). If I gently pull on the winding lever or operate the MLU lever, it trips the
shutter.

By doing some "experiments", I found that lifting the mirror part-way (~half way) with the MLU lever while simultaneously firing the shutter works 99% of the time, i.e. mirror flips up, shutter fires and mirror returns. So I (partly) disassembled the body to get a closer look at what is happening: When the mirror gets stuck, giving the lever at the top left hand corner of the mirror box (the one that looks like it is touching "something" that sticks out of the curtain "shaft") does not move far enough towards the back of the camera. Simply "touching" it with the tip of a pinzette completes the shutter cycle (i.e. shutter fires and mirror flips down again), I guess that there is some tiny adjustment by a fraction of a millimeter may be all that is required to get it working again.

Looking closer at the parts that are involved in this, I noticed that there is a tiny, yellow plastic O-ring around some stud/trunnion that looks strangely deformed and may be the source of the issue. Carefully studying the LX Repair Manual, I get the funny feeling that this may be the part "B72" ("Mirror-charge column collar") mentioned on page 31 of that manual.

Is there any point in sending this beauty to have some CLA applied to it might it be a lost cause due to lack of parts? Since I'm located in Germany, I'd prefer one of the few shops around here that still offer service for file SLRs. Anyone got an idea what the price tag on such a service - if it is possible?

Thanks & Regards
Marc

11-15-2020, 12:26 PM - 1 Like   #2
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Something to note if you do decide to send it in for a CLA, this is extremely similar to the symptoms of a cracked circuit board which most technicians and repair shops will not be able to fix or repair, so they might be off put by it. I had an LX recently repaired for this and some shutter issues in the US by Eric, and he was able to return it to working order. Unknown if that was via replacement parts or fixing the existing collar.
11-16-2020, 12:20 PM   #3
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Wow - do I feel stupid now :-)

Hi all

Seems like I was looking at the wrong "end" for the shutter problem. After finding out that the "trigger rate" for the shutter depends on the orientation of the camera body - i.e. when it was pointing straight up the "success rate" was like 90-95% - I thought about this observation for a couple of minutes and started to feel incredibly stupid

Of course it is the (now missing) light seal across the top of the mirror box! The foam that is supposed to be there provided - when compressed by the mirror flipping up - the "signal" that the mirror is now fully up and the shutter can open. So when the camera is pointing straight up the mirror travels just a tiny fraction more as the respective springs do not have to "lift" the full weight of the mirror assembly and that is sufficient to generate the "Mirror Up" signal. Silly me not thinking of this...

So I think this is one more LX rescued from becoming a book end

Sorry for creating noise...

Regards,
Marc
11-16-2020, 01:53 PM - 1 Like   #4
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If you want a CLA, Robin at Harrow Technical is still taking on some work although he is partially retired. He managed to fix my LX which looked like it had the classic sticky mirror problem, but it turned out to be something electronic. He then repaired it a second time when I dropped it on a rock.
K.

11-17-2020, 04:23 PM - 1 Like   #5
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Even if the immediate problem appears to be solved: I was able to get a perfect service for my old LX from Kamerazeit in Lübeck.
11-19-2020, 04:24 AM - 1 Like   #6
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QuoteOriginally posted by wkraus Quote
Even if the immediate problem appears to be solved: I was able to get a perfect service for my old LX from Kamerazeit in Lübeck.
Another nod to Kamerazeit. He is authorized Pentax service.
11-20-2020, 02:58 AM   #7
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QuoteOriginally posted by yucafrita Quote
Another nod to Kamerazeit. He is authorized Pentax service.
I got in contact with them ("Kamerazeit") already and will definitely let them give some TLC to this beauty :-) The quote he gave me for doing an assessment is so tempting that it would be foolish not to do so.

It's the most "sophisticated" film SLR in my collection and deserves to get some attention. In comparison to my Nikon F4s and Minolta Dynax 9, it looks and feels like a Lotus Elise parked next to some clunky road train. I really don't think that I'd ever actually *need* the absurd shutter times of a Dynax 9 - 1/2000th ought to be fast enough for 99.9% of what I actually shoot on film - and for everything else I have my 5D Mk. IV :-)

BTW: Any recommendations for a entry- to mid-level Pentax DSLR? Anything I should look for in the "Used" market or - even better - which model to avoid?

Regards,
Marc
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