Locked-up mirror - Pentax Spotmatic f

[Joao]

Hello
My Pentax Spotmatic F suffers from the "Stuck mirror syndrome". It is quite easy to repair, with a little alcohol or Ronsonol, plus a drop of lubricant and the camera starts working again.
But the problem recurs too often.
If I leave the camera on the shelf for some weeks there we go : stuck mirror, opening the bottom, cleaning, lubricating. Sometimes the mirror gets stuck after only a few days without using it.
Is there any more radical repair that can prevent this? Any specific part worth replacing???
An additional question about gear lubrication: do you recommend silicone oil for cameras??
I am grateful for opinions and suggestions.
Regards
Joao

 

[wwfloyd]

You seem pretty well-versed on the camera. But, you have not mentioned the mirror bumper foam... any chance it's sticky?

 

[farlymac]

I use silicon oil to lube the "Canon squeal" out of my AE-I P's, but that's about the only place. The bumper foam issue mentioned by wwfloyd could be your problem, but there is also the sticky shutter brake issue which could be affecting it. A complete CLA would help, what with the age of that camera.


PF

 

[Phil_F_NM]

Use only synthetic watch oils where oil need to go. also, replace all the foam inside and out.

Phil Forrest

 

[retinax]

Mine has the same problem, and I have also oiled the place under the bottom plate where the mirror can be released... to no avail. Mirror bumper foam is replaced and if anything too hard.
I'll need to investigate the shutter brake.
I recall having read that silicone oils tend to migrate too much for camera purposes.

 

[johnf04]

The mirror is sticking up because the second shutter curtain isn't completing its travel. The cause for this is probably dirt and dried lubricant in the shutter shaft bearings. The cure is to remove the mirror box, clean the bearings, reassemble the camera. This website has repair manuals.

https://learncamerarepair.com/

 

[Barry Kirsten]

Thanks for the link, John. I have a Spotmatic and an SV, both of which need CLAs, which I'll now tackle myself with the help of these manuals.

 

[Joao]

I am grateful for your input.
The foam seems to be OK - and the problem is temporarily solved after cleaning the place under the bottom plate where the mirror is released. I can replace the foam anyway...
The sugestion by johnf04 makes sense and I will go that way.
Thank you all
Joao

 

[monopix]

If you can fix the problem by cleaning and lubricating, then you know what the problem is. If it doesn't continue to work then it's probably because you're using the wrong lubricant. You haven't said what part it is you are lubricating or what type of lubricant you use so can't say more but I would look again at what you are using and try something different. As a general rule, the slower the moving part the thicker the lubricant required.

 

[Joao]

If you can fix the problem by cleaning and lubricating, then you know what the problem is. If it doesn't continue to work then it's probably because you're using the wrong lubricant. You haven't said what part it is you are lubricating or what type of lubricant you use so can't say more but I would look again at what you are using and try something different. As a general rule, the slower the moving part the thicker the lubricant required.

I put a drop of lubricant (after cleaning) in the gears "A" and under the moving part "B". I used a thin lubricant recommended for firearms, and I tried once the silicone oil (the results were disappointing)

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Any aditional recommendation will be welcome
Regards
Joao

 

[monopix]

I don't know exactly what those parts do but I would guess they're not intended to be lubricated. Maybe just try cleaning without lubricating afterwards. You might need to dismantle them to clean them properly.

Have you checked the repair manual?

http://www.pentax-manuals.com/manuals/service/spotmatic_sm.pdf

There's a bit about the reassembly of these parts. No lubrication is mentioned.

 

[retinax]

I think the idea is that as moving that lever can un-freeze the mirror, it must need lubrication if it's not working right. But everything points to the problem coming from elsewhere...

 

[farlymac]

You normally do not lubricate film transport and winding gears because that would attract dirt, and clog up the works. I've cleaned out a few SLRs that ran just fine after a good de-greasing. Ball bearings though on the ends of the curtain shafts might require a smidgen of grease.


PF

 

[Joao]

Thank you again – especially for the link to the repair manual.
I think I may have found the solution. My first atempts were based in this video
https://www.youtube.com/watch?v=vqInG6Fd7tg
(first 3 minutes are boring and can be ignored). It points to the solution I mentioned, it results to some extent, but the rationale behind it is not clear. There are other vídeos with this aproach.

But I found another vídeo that seems more logical to me. There is a lever that needs to be slightly grinded – I used to lubricate it. The gears I mentioned as “A” are left undisturbed.
https://www.youtube.com/watch?v=0HSg795F5qY

I will carefully read the repair guide and, unless some new aproach is recomended, I will do as this vídeo says. It makes sense.
I hope to post good news soon.
Your input was much apreciated.
Best Regards
Joao

 

[farlymac]

Thank you again – especially for the link to the repair manual.
I think I may have found the solution. My first atempts were based in this video
https://www.youtube.com/watch?v=vqInG6Fd7tg
(first 3 minutes are boring and can be ignored). It points to the solution I mentioned, it results to some extent, but the rationale behind it is not clear. There are other vídeos with this aproach.

But I found another vídeo that seems more logical to me. There is a lever that needs to be slightly grinded – I used to lubricate it. The gears I mentioned as “A” are left undisturbed.
https://www.youtube.com/watch?v=0HSg795F5qY

I will carefully read the repair guide and, unless some new aproach is recomended, I will do as this vídeo says. It makes sense.
I hope to post good news soon.
Your input was much apreciated.
Best Regards
Joao

That second video really does show what can happen to older cameras. After so many windings and releases the levers can develop deformities that cause them to catch where they are not supposed to. The repair should last quite a while, Joao, and doesn't require a lot of tear down to the camera.

PF

 

[monopix]

Given that lubricating it did fix the problem, albeit temporarily, I would be tempted to put a smear of grease on the end of the lever first to see if that gives a more permanent fix than the oil you previously used. Once you grind some metal off there's no going back so try everything else first would be my suggestion.

 

[Joao]

Given that lubricating it did fix the problem, albeit temporarily, I would be tempted to put a smear of grease on the end of the lever first to see if that gives a more permanent fix than the oil you previously used. Once you grind some metal off there's no going back so try everything else first would be my suggestion.

Wise words. There is nothing to loose in trying.
I will go that way .
I will be satisfied if I can shoot a few rolls without problems .
Outcome will be reported.
Thanks again
João

 

[retinax]

Ugh, while I watched the repair video, I played with my Spotmatic and it has now locked up in a new way. Mirror is down, shutter is cocked (80% sure), advance lever locked, shutter release can be pressed down like in uncocked state and nothing happens. The weirdest part: The L-shaped lever is in cocked position but the black lever (the one the is supposed to slip off the L-shaped one, as discussed here) that moves the mirror isn't resting on it, it's in the released position!