Olympus OM-40 Program - Mirror stuck on firing position

[LeoSerra]

Hi,
I bought this camera on a carboot sale. I bought it cheap enough knowing that there was potential of it not working properly.

I'm trying to fix it.

The issue is that the mirror is stuck on the firing position (up position) and I'm certain is not batteries or magnets.

Imagine that you push the advance lever and the camera is ready to fire. Once you shoot the mirror closes and does not come down again.
You need to open the bottom and push a small lever (picture 1, in red, small protruding lever) so that the mirror comes down and you can rearm again. The idler gear seems to work fine as it turns fine with the expected fit of the "two teeth" gear.

However underneath the idler gear, the protruding lever acts on the stop you see on picture 2, circle 2. It seems when you arm the camera, this "stop" enters the opening on that gear and holds it.
When it fires, the mirror goes up and this "stop" does not go all the way back, completing its cycle and does not go back enough for the gear to unwind.

I'm not sure if the bigger arm, next to the protruding lever, is the one responsible to push it back all the way, enough to complete the mirror cycle. I took it out and checked the spring tension, and I think its strong enough that it should push the small lever without issue.
I assembled it again as originally was.

If anyone has any knowledge on this specific camera that can lay some help, I would appreciate it. I also have the repair manual, but I can't make sense out of it.

This is the mechanical issue, I'll then go to check the electricals

This would go pair well with my OM-10.

Thanks for checking and welcome any suggestions.

 

[monopix]

Have you checked the shutter is fully closing? It's the shutter closing that will release the mirror.

 

[P C Headland]

If you haven't already, do try changing the batteries.

I colleague at work had an OM4Ti that exhibited similar behaviour. It would fire, the mirror would go up and stay up. You'd have to switch the shutter to "B" (IIRC) and the mirror would come down again. Fresh batteries cured it.

 

[reddesert]

In cameras of this generation with electronically controlled shutters (OM-2, OM-40, Nikon FE, and so on), "mirror doesn't return" is typically a sign of weak batteries, or (less often) an electronic fault. Your best bet is to try nice fresh batteries. I know the OM-40 / OM-PC has a battery check, but even if the battery check makes a noise, older batteries might be too weak to finish the exposure.

The OM-40 does not have a mechanical shutter speed other than B, but I think when you get the mirror-stuck-up, you can switch the mode to 'manual' and speed to 'B' (as P C Headland suggested), and the shutter should finish and the mirror return. If that works, there is likely nothing wrong with the mechanical elements of the camera, and it's either batteries or less likely an electrical fault.

 

[LeoSerra]

Hi,

Sorry for the silence, the weekend was pretty full.

Thanks for the suggestion so far.

I was able to test some of them.

@monopix the shutter does not open while the mirror is up. When I push the small lever, then it opens and the mirror goes down.

To @reddesert point it might be more serious than just some fresh batteries.

I bought some fresh ones and tried them with no effect on the symptoms I'm having. The battery check does not provide any beep (like my OM-10) and switching to manual and Bulb mode, does not make the mirror go down all the way. I have to trigger the small lever manually.

I might have electronic issues. I'll try to see where the battery flow stops. I just didn't want to disassemble the camera fully
I have a multimeter and will try to get more information.

If there are any more suggestions that would be great. I'll let you know of any progress on this search.

Thanks for the support!

 

[monopix]

@monopix the shutter does not open while the mirror is up. When I push the small lever, then it opens and the mirror goes down.

So your problem is not that the mirror doesn't return but that the shutter fails to open. That can happen if the mirror foam has been replaced with foam that is too thick and which stops the mirror from fully rising. Try pushing up on the mirror.

 

[LeoSerra]

@monopix The foam is very thin. I think this camera never had a CLA in its life. That was something I had planned in case I would be able to make it fully functional.
I can pull the mirror up, and it comes down on its own (when armed or had already taken the shot and I pull the small lever I mentioned earlier)

At this point I was trying to check the electronics, but its a bit too much for me. I have to take the courage to completely disassemble the top part of it, including the circuit strip. I could measure current under the mode selector (between 0.2 to 0.5V), but after that is anyone guess.

 

[reddesert]

If the battery check doesn't light and beep, then the camera isn't getting power. This could be any number of things I guess, and I don't have any experience with debugging an OM-40. However, the two things I would check for continuity and try to clean are: the battery chamber contacts and wires, and the main mode switch. If you have 0.2-0.5 V somewhere under the mode switch, that suggests some continuity, but it is a little weird that it isn't the full voltage (3 V ?) IMO.

This is based on my experience/feeling that electro-mechanical parts and connectors are much more likely to cause problems than actual failures of electronic components (resistors, ICs, etc).

 

[LeoSerra]

Hi,

Thanks for all the input you have gave me.

Today I inhaled very deep and started to disassemble the camera, as I was willing to go to the end and try to catalogue everything.

Thankfully I didn't need to go to the end, as at some point, by accident, noticed that by taking a screw holding the circuit above the prism, the mirror was coming down.
Immediately I though there was a bad contact, but it was not the screw in itself.

Then I noticed that arming the camera, and shooting the mirror was still getting stuck, but bending the circuit would trigger it to go down. The next step was to pinch the circuit and trying to find the point of bad contact. It was the grey wire you see on the picture. I soldered it again and it worked.

The mirror comes down every time now. The battery check beeps, and the other modes show the indicators through the viewfinder. Even the led at the front of the camera lights up.

I will have now to get the speed film speed selector correct. Its a bit loose and I'm not sure how to calibrate it now.

This mode does not seems to be around many times, but in this case, getting this far is a victory to me and having two Olympus OM could be the start of a collection

I have a Nikon FE10 to try and achieve the same results as this one.

I hope it can help anyone with a stuck mirror where the solution is quite different from the usual ones.

Thanks, I really appreciate all the help!

 

[gabrielcamposbr]

Hi,

Thanks for all the input you have gave me.

Today I inhaled very deep and started to disassemble the camera, as I was willing to go to the end and try to catalogue everything.

Thankfully I didn't need to go to the end, as at some point, by accident, noticed that by taking a screw holding the circuit above the prism, the mirror was coming down.
Immediately I though there was a bad contact, but it was not the screw in itself.

Then I noticed that arming the camera, and shooting the mirror was still getting stuck, but bending the circuit would trigger it to go down. The next step was to pinch the circuit and trying to find the point of bad contact. It was the grey wire you see on the picture. I soldered it again and it worked.

The mirror comes down every time now. The battery check beeps, and the other modes show the indicators through the viewfinder. Even the led at the front of the camera lights up.

I will have now to get the speed film speed selector correct. Its a bit loose and I'm not sure how to calibrate it now.

This mode does not seems to be around many times, but in this case, getting this far is a victory to me and having two Olympus OM could be the start of a collection

I have a Nikon FE10 to try and achieve the same results as this one.

I hope it can help anyone with a stuck mirror where the solution is quite different from the usual ones.

Thanks, I really appreciate all the help!

Hey Leo, hope that you're doing good! Glad to hear that you've fixed your problem...


So, recently i also bought an OMPC (aka OM40) on eBay, the seller said that everything was working perfectly...
But when the camera arrived i noticed some problems

1. The light meter isn't working properly.
   
   I've tried it on auto, manual, pointed to the sun, flashlight and keep stuck between 1 and 2. BUT i noticed that when i lift the ISO button slightly, I can see different numbers (4, 8, 16...), but it only goes up to 16, nothing above that!
   On Aperture mode i can see up to 250 if i slightly lift up the button... But not in any other mode... (i've changed batteries twice, unfortunately there's no SR44 batteries to buy here.)
   
   
   
   
   
   
2. Also, i have noticed that the shutter speeds aren't working on manual mode... I don't know if it's totally related to the batteries (maybe an SR44 can fix everything and i'll have to find it real hard, maybe buy from eBay or any international supplier...)
   Do you think that it's a problem that can be solved easily? I'm not an expert on repair but i know how to get things done, potentially the gear isn't aligned properly....

I think that it'll be way harder to return it, so i'm trying the best that i can do only to fix the shutter speed dials...

 

[LeoSerra]

Hey Leo, hope that you're doing good! Glad to hear that you've fixed your problem...


So, recently i also bought an OMPC (aka OM40) on eBay, the seller said that everything was working perfectly...
But when the camera arrived i noticed some problems

1. The light meter isn't working properly.
   
   I've tried it on auto, manual, pointed to the sun, flashlight and keep stuck between 1 and 2. BUT i noticed that when i lift the ISO button slightly, I can see different numbers (4, 8, 16...), but it only goes up to 16, nothing above that!
   On Aperture mode i can see up to 250 if i slightly lift up the button... But not in any other mode... (i've changed batteries twice, unfortunately there's no SR44 batteries to buy here.)
   
   View attachment 412306
   
   
2. Also, i have noticed that the shutter speeds aren't working on manual mode... I don't know if it's totally related to the batteries (maybe an SR44 can fix everything and i'll have to find it real hard, maybe buy from eBay or any international supplier...)
   Do you think that it's a problem that can be solved easily? I'm not an expert on repair but i know how to get things done, potentially the gear isn't aligned properly....

I think that it'll be way harder to return it, so i'm trying the best that i can do only to fix the shutter speed dials...

Hi Gabriel,
I realize in the Americas that's the name given to the same camera.
Today I continue to work on the camera, on the cosmetic side of it, and realized that the mirror was stuck again. New batteries and it's working fine. So it seems it might be draining the batteries even when not in use.

When I was checking the mirror issues I took a small lid on the bottom of the mirror box. I think that's where the light sensor is. Maybe you need to take it off (its in place with a small dab of glue) and check if there is any amount of dust, or something else. When I bought mine it had a web of fungus. If you need to go further I'm afraid you'll need to disassemble the camera fully.

I took the top cover and cleaned all circuitry with alcohol and all dust and fungus blown away.

For the speeds it seems some kind of bad contact under the speed selector. Take it off and clean the circuit with alcohol. Carefull there is a small metal sphere bearing under. Don't loose it.

You might need to check the aperture of the lens as it might be limiting the speeds.

Here in Europe the battery is LR44 and its very common as it's used in many other small electronics.

I hope this helps.
I'm on my phone, but I can attach the repair manual of this camera. Not very descriptive but helped to assemble back the camera.

 

[reddesert]

LR44 are alkaline batteries and SR44 are silver oxide, but for this camera it should work with either, as long as the batteries are good (new-ish, not drained). The discharge curves of the two types are different and SR44 are more desirable, but if a camera doesn't work with new LR44s, SR44 will not cure it.

 

[LeoSerra]

I agree @reddesert , its just that LR44's are commonly sold in supermarkets here. SR44's are more expensive and I have to order online, so its a good trade. I will take them off while not using.
In my case the camera is fully functioning, no issues now.

@gabrielcamposbr the size of the service manual is around 12.4MB and I can only upload 2MB. I don't want to start sharing links with downloads.
Have a look around with Google, I found the service manual at "scribd" website. With a trial, you should be able to get it.