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Prasanna
Tinkerer
Username: Prasanna
Post Number: 19
Registered: 10-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, October 27, 2009 - 07:17 am: | 
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Steve Shepherd Hi! if you are around please help. I bought this Praktica L on ebay. It was all jammed up. I opened the front shutter knob plate with the pentaprism and cleaned and lubed it. I also cleaned and lubed the rear chassis with the winding crank and the shutters. The shutters and timers work well now, smoothly. The front also works except for the mirror return. I have to push the little flat piece of steel holding up the mirror for it to come down each time I operate the shutter. I don't perceive any damage or misalignment in the mechanism. The camera had not been used for a long time and possibly allowed to rust. Is there away I can tackle this mirror problem? Thank you, regards, subbarayan |
Steve_s
Tinkerer
Username: Steve_s
Post Number: 166
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, October 28, 2009 - 04:42 am: |
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I've never had to set foot in this area, Subbarayan, but I have had a look at a scrap unit to see what I can see.
Firstly, I'm assuming that the horizontally moving pin attached to the 2nd blind at the top-right of the shutter unit is correctly operating the release lever, and that when it does, the lever on the front-panel unit which is pushed forward as you cock the shutter is returning normally at the end of each firing. Presumably you are lowering the mirror by pressing the tab actually holding it up, at the top-right of the mirror-box (or the top-left looking through the flange)?
On my scrap unit I can see a light tension spring working on the lever this tab is attached to, but this spring is what engages the tab to hold the mirror up while the shutter fires. The rest of this lever is completely hidden in the mess of levers to the right of the mirror-box, so I can't see how it is actually operated, but it does seem to operate positively - i.e. it is forced to the position where it releases the mirror as the front-panel cocking lever returns, therefore I don't think it is likely that the problem is caused by sticky lubricant.
It looks to me as though the tab (the release tab, not the one on the mirror) is a factory adjustment. On my unit there is a tool mark on the slot in the body behind it where it might have been levered. With the mirror stuck up, is the release tab very close to the point where the mirror is released? Have a look at it at the 1 sec speed. If the tab is moving OK - just not quite enough to release the mirror - I would be inclined to try bending it very slightly towards the back of the camera. You will probably have to take off the front-panel unit again, so that you can get a tool in behind the tab to give you something to lever against.
Regards, Steve. |
Prasanna
Tinkerer
Username: Prasanna
Post Number: 20
Registered: 10-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, October 28, 2009 - 09:05 am: |
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Thanks Steve for the kind and prompt response. I figured the problem and solved it too. I opened up the body, the top and the front modules apart. Amazed at the modular neat design; reminds me of the VW Beetle. There is a shutter operating module attached to the left of the mirror box. There is a lever that operates the shutter and when it kicks back to the idle position [toward back of the camera] it is supposed to drag a small ear that is attached through the wall opening to the mirror chamber to the lever that releases the mirror to come down. This ear [I don't have a better name for it!] piece was bent away and was not getting the purchase from the shutter operating lever. It is very small and hidden from sight because of the maze of levers as you mentioned. As it is all mild steel I bent it back to shape and the mirror module worked fine.
I shall post some pictures tomorrow for your interest. I got misled by reading Tomosy's book that this happens due to the weakness of the mirror return spring. Actually I found that the spring on this ear piece lever is redundant. The mirror returns by its own spring at the hinge in the back.
The shutter module was all dirty and almost rusty. I cleaned that up with alcohol and lubed it. It works fine. All the modules are working well and timing well too.
Unfortunately, the lever in the cocking mechanism that sets the trigger in the shutter button module was very weak and broke. metal fatigue, I guess. So I now have the camera all repaired and ready to go but it is missing the firing pin! I learned a lot through this exercise!
Thanks again, regards, Subbarayan |
Prasanna
Tinkerer
Username: Prasanna
Post Number: 21
Registered: 10-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, October 28, 2009 - 10:47 am: |
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Steve Hi! Here are a couple of pictures that may illustrate the point of the problem. Sorry that the pictures are not very good. Regards, subbarayan |
Prasanna
Tinkerer
Username: Prasanna
Post Number: 22
Registered: 10-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, October 28, 2009 - 10:54 am: |
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Sorry; there is some problem with the website; I am unable to post the pictures. Shall try later. subbarayan |
Prasanna
Tinkerer
Username: Prasanna
Post Number: 24
Registered: 10-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, October 28, 2009 - 11:10 am: |
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I have posted the pictures in the link below.
http://picasaweb.google.com/lh/photo/-bQMpcvRHa92HBjT_AMTCQ?feat=directlink |
Prasanna
Tinkerer
Username: Prasanna
Post Number: 25
Registered: 10-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, October 28, 2009 - 11:14 am: |
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Another picture in link below.
http://picasaweb.google.com/lh/photo/H3q4KILeR0ty3HSiGXKSmQ?feat=directlink |
Steve_s
Tinkerer
Username: Steve_s
Post Number: 167
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, October 29, 2009 - 12:38 am: |
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If you're keen to get it going and can't find a 'spares' camera locally, and if the lever that is broken is the one that rotates below the speed control with the downward pointing leg, I have one in a PLC3 which you could have for postage cost.
The PLC3 being a later model, I couldn't be absolutely certain the part is identical, but I should think it is very likely. If you're interested contact me via the forum. |
Prasanna
Tinkerer
Username: Prasanna
Post Number: 26
Registered: 10-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, October 29, 2009 - 12:52 am: |
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Thanks Steve; I will keep this one for spares. I have quite a few Prakticas in the L-series. I bought this only to learn the innards of the system. And it has served that purpose well. Thanks again. Regards,
subbarayan |
