| Author |
Message |
    
Cmedin
Tinkerer
Username: Cmedin
Post Number: 19
Registered: 09-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, November 25, 2007 - 06:16 pm: | 
|
Hi all,
Just picked up a pile of stuff today. $100 for an OM2, motor drive, K1000, 50 and 28mm Zuikos, some Pentax glass and offbrand stuff, Minolta motor winder yada yada... very happy.
The OM2 is cosmetically perfect, and everything seems to be in good shape... with one exception. When I got it the shutter would stick open (with new batteries, PX76), but after working it at each speed over and over again it started working fine ALMOST everywhere. At 1/500 and 1/1000 maybe one out of ten firings causes it to hang open; it either snaps shut again after 1-5 seconds or if you crank the winder a few times it'll shut itself.
Should I just continue to work the shutter and hope it'll come loose, or is this something requiring more in-depth work?
thanks in advance! |
Cmedin
Tinkerer
Username: Cmedin
Post Number: 20
Registered: 09-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, November 25, 2007 - 06:17 pm: |
|
Tried to edit the post but it won't let me for some reason... I did read up on improper batteries causing sticky shutters, but as far as I know the PX76 is the proper one for it and they're brand new. |
Poum
Tinkerer
Username: Poum
Post Number: 5
Registered: 09-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, November 29, 2007 - 02:00 pm: |
|
Cmedin, is it the same problem I describe in this thread:
https://kyp.hauslendale.com/classics/forum/messages/2/10719.html?1196369975
? |
Cmedin
Tinkerer
Username: Cmedin
Post Number: 21
Registered: 09-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, December 01, 2007 - 05:11 pm: |
|
Hi Poum, it's similar but not quite...
At this point, having exercised the shutter thoroughly, I have arrived at this state:
In Auto mode the meter reading works perfectly, agreeing with my Luna Pro.
In Auto mode, the shutter speeds are several stops slower than the indicated reading ("preview") in the viewfinder.
In Manual mode, the metering is several stops off, requiring much longer shutter speeds than it should. Once or twice something's happened and suddenly Manual mode agreed perfectly wuith Auto (set the shutter to the auto reading and switch and the needle was in the middle), but most of the time that is not the case.
In Manual mode, the shutter fires what appears to be very accurately every single time.
So I can use Auto mode for a meter reading, set the shutter, flip to Manual and expose and get good shots... but Auto alone or Manual alone do not work properly.
I just got the service manual for it, but haven't had a chance to read it yet. I can't help but wonder if there's some point in the circuit that causes both problems: the Auto exposure being off from the reading and the Manual reading being off. |
Cmedin
Tinkerer
Username: Cmedin
Post Number: 22
Registered: 09-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, December 02, 2007 - 09:08 am: |
|
OK, I was wrong about the metering being just plain off in Manual mode. It looks like no matter what the speed ring is set to, it's reading it as 1/1000. I arrived at this by playing with manual mode (film speed and aperture settings) until I got the needle centered, then switched over to Auto and got a 1/1000 reading. I gather there's a variable resistor (potentiometer?) that's being moved by the ring, so either something is stuck or plain shorted out seeing as it's one of the extremes of the readings. |
Poum
Tinkerer
Username: Poum
Post Number: 6
Registered: 09-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, December 04, 2007 - 01:30 am: |
|
You can start by unmounting the speed ring and clean the contacts. This is a known issue on OM-1/OM-2. |
Spyderman
Tinkerer
Username: Spyderman
Post Number: 7
Registered: 01-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, December 17, 2007 - 09:23 am: |
|
shutter speed in auto without film inside will be several stops longer than shown in viewfinder. insert film because the light is metered off the film. pressure plate is black, film is grey.
the manual mode issue: clean contacts under shutter speed ring. take care not to lose a small metal ball.
good luck. |
|
