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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: Mon, 04 Dec 2006 08:37:53 -0500
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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