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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: Fri, 01 Dec 2006 08:07:58 -0500
Pin CE1573 goes through slot in CE1561 main tube. This is what prevents 
lifting of ring. End of CE1573 fits into slot of CE1548.

On most other OM lenses, a forked tab would protrude through this slot 
in the main tube, and a simple shoulder screw on the diaphragm ring 
would engage that tab. Easy lift-out. By now, you are probably done, but 
I thought I'd explain anyway.


___________________________________
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, John.  I can see the L shape in the parts diagram but don't 
> recognize anything that I would have thought would interfere with 
> pulling the ring straight up.  But I'll certainly follow your 
> instructions.  I'm intrigued now to see what's actually holding it in 
> place and, of course, to see what's preventing the full range of motion. 
> I'm suspicious that the pin was simply misplaced when the lens was last 
> assembled.  Perhaps it's on the wrong side of whatever mechanism it's 
> supposed to mate with.  I'll soon see.
> 
> Thanks,
> 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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