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[OM] Re: 28mm f/2.8 repair advice

Subject: [OM] Re: 28mm f/2.8 repair advice
From: John Hermanson <omtech1@xxxxxxxxxxx>
Date: Tue, 05 Dec 2006 08:22:37 -0500
Only a few dozen times. :-0

___________________________________
John Hermanson
Camtech Photo Services, Inc.
21 South Lane, Huntington NY 11743
631-424-2121 | Olympus OM Service since 1977
http://www.zuiko.com  |  omtech1 AT verizon.net


Chuck Norcutt wrote:
> Thanks again, again.  My guess is that you've never seen this particular 
> malady before, eh?
> 
> Chuck Norcutt
> 
> John Hermanson wrote:
> 
> 
>>excellent!
>>
>>___________________________________
>>John Hermanson
>>Camtech Photo Services, Inc.
>>21 South Lane, Huntington NY 11743
>>631-424-2121 | Olympus OM Service since 1977
>>http://www.zuiko.com  |  omtech1 AT verizon.net
>>
>>
>>Chuck Norcutt wrote:
>>
>>
>>>Thanks for the help.  The problem is fixed.  The lens must have been 
>>>repaired and mis-assembled some time before I got it and apparently I've 
>>>never tried to use it until recently or, if I did, never attempted to 
>>>set it wider than f/5.6.
>>>
>>>The problem was that the diaphragm stop down lever driven by the camera 
>>>(CE1049) which is supposed to fit into the wider of two notches in 
>>>CE1584 was on the outside of the notch and not inside the notch.  The 
>>>aperture control pin (CE1573) also fits into a notch in CE1584 but into 
>>>the smaller of the two side-by-side notches.  It was properly in the 
>>>small notch but, since the stop down lever was outside of its own notch 
>>>in CE1584, when the aperture control pin would cause CE1584 to rotate 
>>>CE1584 would run into and jam against the misplaced stop down lever 
>>>before completing its full travel.
>>>
>>>It took removing the front lens assembly as you suggested to see what 
>>>the problem was but the fix had to be implemented from the back by 
>>>removing the mount so the stop down lever could be lifted and inserted 
>>>into the notch in CE1584.
>>>
>>>Add "mis-assembled 28/2.8" to your list of symptoms and fix file.
>>>
>>>I think this may be the first time I've ever "easily" removed a thread 
>>>locked lens assembly with a little bit of acetone.
>>>
>>>Thanks again for the help.
>>>
>>>Chuck Norcutt
>>>
>>>
>>>
>>>John Hermanson wrote:
>>>
>>>
>>>
>>>
>>>>The pin on the 28 2.8 is L shaped and connects to the diaphragm control 
>>>>cam through a slot in the main tube.  To remove the ring, you'll have to 
>>>>take out the 2 screws holding the pin in.  Unscrewing the front lens 
>>>>assembly, which would expose the diaphragm mechanism, should reveal what 
>>>>the problem is.
>>>>
>>>>___________________________________
>>>>John Hermanson
>>>>Camtech Photo Services, Inc.
>>>>21 South Lane, Huntington NY 11743
>>>>631-424-2121 | Olympus OM Service since 1977
>>>>http://www.zuiko.com  |  omtech1 AT verizon.net
>>>>
>>>>
>>>>Chuck Norcutt wrote:
>>>>
>>>>
>>>>
>>>>
>>>>>Hey, here's a real, live, nitty-gritty, on-topic OM post!
>>>>>
>>>>>I have a 28mm 2.8 which will not open (using the diaphragm ring) to more 
>>>>>than f/5.6.  The diaphragm blades open fully when the DOF preview button 
>>>>>is not depressed but the diaphragm ring can't be rotated to either f/4 
>>>>>or f/2.8.  It hits a hard stop at f/5.6.
>>>>>
>>>>>I assumed that there must be a problem with the detent ball but was 
>>>>>surprised when I removed the filter/detent ring and found that the 
>>>>>detent mechanism is fine and there is no appreciable wear on the ring.
>>>>>
>>>>>I tried rotating the diaphragm ring again without the detent ring and 
>>>>>ball installed and it still hits a hard stop at f/5.6.  Then I tried to 
>>>>>lift off the diaphragm ring and was surprised to discover that I 
>>>>>couldn't.  I can lift the side opposite what I'll call the diaphragm 
>>>>>coupling pin (CE157300 on the parts diagram) but that pin acts like it 
>>>>>has a hook on the end.  The pin side lifts no more than 1/2mm and stops 
>>>>>cold just as though what I think should be a flat bladed pin has a hook 
>>>>>on the end and is catching on something.
>>>>>
>>>>>Any suggestions?  If I remove the lens mount will I be able to see the 
>>>>>inside of the barrel and figure out what the obstruction is?  I guess I 
>>>>>could also remove the two screws attaching the diaphragm ring to the 
>>>>>coupling pin but I hate to disassemble what I don't have to.
>>>>>
>>>>>Thanks,
>>>>>Chuck Norcutt
>>>>>
>>>>>
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>>>>>
>>>>
>>>>
>>>>
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>>>>
>>>
>>>
>>>
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>>>
>>
>>
>>
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>>
> 
> 
> 
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