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Two40
Tinkerer
Username: Two40
Post Number: 6
Registered: 02-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, April 29, 2008 - 07:14 am: | 
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Hello folks.
I recently purchased two OM-1's and am very happy with them. This really is a neat SLR. Well worth every penny and well worth repairs I believe.
Camera 1 has everything working except a missing timer lever.
Camera 2 has everything working except a missing timer lever and an extremely inaccurate light meter. When switched on it barely goes up while facing a light source.
Now I don't care for the timer lever but would like to fix it eventually. The light meter on camera 2 however is something I'd like to fix and I wouldn't mind transfering parts over from camera 1 as it is a tidier unit. What would be involved in transfering parts and which ones are the likely culprit? Where would I be able to find some pictures maybe or any instructions on the process? I wouldn't even know where the light meter is to begin with which says a lot about my experience level with fixing SLR's. I'm not worried though and am keen to give it a go.
Any help appreciated as always. Thanks a bunch.
George |
Rick_oleson
Tinkerer
Username: Rick_oleson
Post Number: 565
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, April 29, 2008 - 04:03 pm: |
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First, are you sure that the meter responds to light AT ALL? OM1's sometimes fool people because the meter is mechanically coupled to the shutter and aperture rings and it is possible to make the needle move even when the meter is off or has no battery if you select extreme combinations of shutter speed, aperture and ASA setting. If it's totally dead, that might be an easier fix: possibilities inlcude a corroded wire to the battery box or a broken plastic screw holding the battery terminal in place. If it's working but very badly off, the first thing I would do is verify that it has a good zinc-air (not alkaline) battery in it, or alternately swap batteries between the two cameras to compare their response. A bad CdS cell can cause very low readings, but they do not really go bad very often. |
Two40
Tinkerer
Username: Two40
Post Number: 7
Registered: 02-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, April 30, 2008 - 02:22 am: |
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Hi Rick, I had a feeling you would come to my rescue  Thanks.
I'm positive it is responding to light albeit very poorly. I shine a torch into the lens and it only responds around the 1/15 and f1.8. Oddly it does change with shutter adjustments but not with aperture adjustments. The battery is the same one I have used to test the other camera and works fine.
Can the cds cell be changed over with relative ease? Is that the likely culprit?
George |
Rick_oleson
Tinkerer
Username: Rick_oleson
Post Number: 566
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, April 30, 2008 - 04:22 am: |
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I don't know how likely it is, frankly, but it is not too hard to check. They are located on either side of the eyepiece. After removing the top cover, you can lift out the little module by removing 2 screws.... then check them by blocking one at a time and seeing what the effect is on readings. If blocking one makes the needle drop and blocking the other does not, then the second cell is bad. If they both respond the same, it's very unlikely that they are both bad to the same degree, so the problem is likely elsewhere in the circuit.
A corroded wire is still a possibility: it may be to the point where it still conducts electricity but can't carry enough current to operate the meter. I would check that first, if for no other reason than it's an easier disassembly. If it's corroded, the worst part will be right at the solder joint to the battery terminal, it will be visible once you get the bottom plate off.
rick : ) = |
Spyderman
Tinkerer
Username: Spyderman
Post Number: 9
Registered: 01-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, May 03, 2008 - 02:20 am: |
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"Oddly it does change with shutter adjustments but not with aperture adjustments."
There are strings that are connected to aperture, shutter speed and onthe other end to the meter galvanometer (needle). If the string comes off a roller it might mare the meter off. Of maybe it has come off the aperture sensing ring ? |
Dmlewins
Tinkerer
Username: Dmlewins
Post Number: 1
Registered: 04-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, April 24, 2009 - 04:42 pm: |
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Would you believe I had an identical problem with the meter only reading at shutter speeds below 1/8th, came to this site (thanks fellas), removed the bottom plate as suggested to check for solder corrosion, found it to be immaculate (incredible since I've had the camera since 1979!), then found (by spotting the + on the battery cover plate) that the replacement battery must have been inserted the upside down (oops) - it was that simple, but without your help I'd have suspected the meter forever as it was doing that with the old battery - guess my daughter flipped it when I lent the camera (stupidly) to her a few years ago and I haven't used it since. Many thanks guys - my lovely old OM-1's finally working beautifully again! Regards from England, Dave. |
Tom_cheshire
Tinkerer
Username: Tom_cheshire
Post Number: 7
Registered: 04-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, April 24, 2009 - 05:19 pm: |
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Maybe of no help to you in this case but I once left my OM1 up-side-down for a few weeks and, when I started up the meter, it did not indicate properly. I cured it by leaving it on with the lenscap on and the camera left in the upright normal position. It was normal again in a day. |
Rick_oleson
Tinkerer
Username: Rick_oleson
Post Number: 870
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, April 25, 2009 - 03:29 pm: |
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all the electrons had rushed to its head and made it dizzy |
Olympfix
Tinkerer
Username: Olympfix
Post Number: 2
Registered: 05-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, May 02, 2009 - 04:38 am: |
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Some models have meters which are string linked to aperture /shutter 'later ones are gear driven. First thing to do is to check whether meter coil is open-pass 1v through blue wire and earth, see if meter needle kicks, reverse to make sure you've got right polarity. If meter is dead, only way is to find a junker and cannibalise the part.Don't know of anywhere in the world with new meters. Not that easy to swap meters over, some have different gear linkages on the base. Count teeth on gear below meter coil. It can drive you stark raving bonkers, if you find one with 13 teeth, and are trying to fit it to a housing which has 14 teeth.Corrosion of brown battery lead is most common meter problem, apart from broken plastic screw. replace whole length to be sure, best to remove mirror housing. Next most common problem is no earth from meter to body. Clean copper strip to body from meter with emery paper and tighten screw. Very rare to have faulty CdS cells. OM1s are wonderful cameras, and the main problems are in the meter. They, of course, work perfectly well without the meter, since they are totally mechanical. |
Leesobing
Tinkerer
Username: Leesobing
Post Number: 30
Registered: 01-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, May 04, 2009 - 05:10 am: |
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http://olympus.dementia.org/Hardware/olympus_hw.html
OM SErvicr manalus |
R_a_feldman
Tinkerer
Username: R_a_feldman
Post Number: 8
Registered: 11-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, May 04, 2009 - 01:40 pm: |
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While you have the camera open, remove all of the black foam from around the pentaprism. It can go bad (or perhaps already has) and corrode the silvering on the prism. Instructions can be found starting at http://olympus.dementia.org/Hardware/tutorials/OM-1CoverRemoval/ |
Olympfix
Tinkerer
Username: Olympfix
Post Number: 6
Registered: 05-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, May 04, 2009 - 03:15 pm: |
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The manuals at the above links are excellent. One other little trap in swapping meters... there are two different meter needle shape configurations- check to make sure the shape of the "steps" of the needle are the same. If not, reshape using tweezers, but be careful- it's easy to break the needle at the step. |
Olympfix
Tinkerer
Username: Olympfix
Post Number: 7
Registered: 05-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, May 04, 2009 - 03:31 pm: |
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And one more... I've seen a lot of OM meters over the past thirty years with sluggish needles caused by a tiny piece of metal shaving caught in the gap between the coil and the magnet. You have to pull the meter out and examine it closely with a loupe to see the problem. |
Bmurf
Tinkerer
Username: Bmurf
Post Number: 1
Registered: 02-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, February 21, 2010 - 12:37 pm: |
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I have a dead meter (OM-1, MD SN#1,477,xxx). Removed bottom plate. Brown wire attached to battery post was corroded and had separated from post.
Attempted to remove wire back to where it was good to do an in-line replacement with good wire. Didn't work out. Wire was bad too far back. I now need to replace the wire. Removed top cover. I assume the brown wire attached to the meter on/off switch (and then wraps around prism before going down into the camera body) is the one I need to replace. Problem is it isn't free/can't be pulled through the body.
Have I identified the correct wire?
How do I replace the wire?
HELP!
PS: I've owned this OM-1 since bought new in 1977 or 78. I want to use it again.I could go with a hand-held meter but I want to try & fix it first. |
Olympfix
Tinkerer
Username: Olympfix
Post Number: 18
Registered: 05-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, February 21, 2010 - 10:56 pm: |
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yes, that's the correct wire, and no, it won't "pull through" it's glued inside the mirror chamber behind the curtains. Sorry, but you have to remove the mirror box to replace the entire wire. Not outrageously difficult 6 screws, -only real trap is to watch that the self-timer activating lever is docked correctly to mate with the shutter activating lever. |
Bmurf
Tinkerer
Username: Bmurf
Post Number: 2
Registered: 02-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 22, 2010 - 02:51 pm: |
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I can't seem to find a web site that details the mirror box removal. Do you know of one? |
Dustinh
Tinkerer
Username: Dustinh
Post Number: 1
Registered: 10-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, October 13, 2010 - 12:02 pm: |
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I've loaded up a new zinc-air battery into my OM-1, however the light meter only displays one meter reading for any situation. (ISO 100, 1.8 at 1 second) The on/off switch also doesn't change the reading (That is, it will display this even while off). Where might I start to fix this? |
R_a_feldman
Tinkerer
Username: R_a_feldman
Post Number: 12
Registered: 11-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, October 14, 2010 - 01:14 pm: |
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First, read the earlier posts in this thread. Then check the battery wires for corrosion by removing the bottom cover and inspecting them. |
