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Zenzaman
Tinkerer
Username: Zenzaman
Post Number: 2
Registered: 11-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, November 19, 2010 - 11:20 am: | 
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i just bashed not one olympus om1n but two 
long story short> for some idiotic reason (the shutter ring seemed a bit stiff) i decided to take it apart and clean it a bit. unfortunately when i took out the shutter ring, the speed sensing ring also got out so i lost the sync between the markings on the shutter ring and the actual shutter speeds. after a lot of tries and another lot of "turn that wheel with your fingernails" really really stupid approaches (i know, i'm sorry!) i found the issue from cameracraftsman on olympus om1 on the internet and finally managed to sync the cameras. unfortunately it seems that while the speeds are correct, the exposure meter severely overexposes (3 stops or more). i know the aperture sensing ring 'tells' the galvanometer what aperture is set through a cord, but the shutter sensing ring is cordless (being an OM1N) so i figured all that wheel and gear turning messed something up. my question is how to fix it!
this is an image of the 'depths' of my reckless journey. (just underneath the "P" letter there's the gear that translates the movement from the shutter ring to the exposure meter - it wasn't in place at the time of the picture)
http://i187.photobucket.com/albums/x228/alinCiortea/camera%20repair/IMG_3539_.jp g
LE> can i subscribe to topics? or do i have to constantly return and check for new posts? i couldn't find any such option. |
Zenzaman
Tinkerer
Username: Zenzaman
Post Number: 4
Registered: 11-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, November 20, 2010 - 03:48 am: |
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i'm back with another attempt to figure it out. i made it this far and realized that the corded wheel connected to the shutter speed sensing ring doesn't turn when the shutter ring is turned (so is (no longer?) connected to the rest of the gears (actually it sometimes turns but only slightly, from whatever friction there is between it and the gear on top of it - i suppose). see image. i don't know if that's how it supposed to be or not but my logic says it should be geared with the others.
http://i187.photobucket.com/albums/x228/alinCiortea/camera%20repair/IMG_3557_2.j pg |
Zenzaman
Tinkerer
Username: Zenzaman
Post Number: 5
Registered: 11-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, November 20, 2010 - 04:37 am: |
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LE: after further tinkering i realized they are in fact coupled, as long as both sensing rings are attached (some kind of a clutch mechanism?). the only thing left now is determining the degree of tensioning of the cord control disc for the 1/1000 setting. |
Olympfix
Tinkerer
Username: Olympfix
Post Number: 37
Registered: 05-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, November 20, 2010 - 05:48 am: |
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There's no clutch mechanism in OM -1s.. continue trying, there are at least three ways of bringing in the exposure meter to correct exposure.. without knowing original settings, it's very tricky. Is it a geared or corded transfer mechanism for the light meter? |
Zenzaman
Tinkerer
Username: Zenzaman
Post Number: 6
Registered: 11-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, November 20, 2010 - 07:20 am: |
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gear-corded i guess  )
there is in fact a kind of 'clutch' mechanism. i finally got the way it works, by determining that the cord control disc only pulls the cord when both sensing rings are in place. i hope my explanation is clear enough...
http://i187.photobucket.com/albums/x228/alinCiortea/camera%20repair/IMG_3557_3.j pg
this image shows the gear '6' removed from the cord control disc. my explanation implies that it's put back together. the aperture sensing ring engages the gear '6'. the shutter speed sensing ring engages the removable gear 1. the cord control disc assembly is made of a geared disc beneath the visibile '4' disc. this '4' disc has a helicoidal slit across its circumference that hosts the cord. if the gear '5' is free, turning the gear '1' (by turning the aperture sensing ring) will spin all the gears EXCEPT for the disc '4'. when the shutter speed sensing ring is turned, the aperture sensing ring is still and therefore will not allow movement of gear '6', that in turn will block gear '5'. by imobilizing this gear, the movement of the shutter speed sensing ring will cause the movement of disc '4' and therefore it will pull the cord that acts upon the galvanometer.
i don't fully understand the relationship between the gear '5', the disc '4' and the geared disc beneath disc '4'. i presume the discs share the same axel but are not connected directly. as the gear '5' seems nitted in place and the disc '4' has a slotted ring that keeps it in place that i couldn't remove (it has barely visible slots that i don't really wanna ruin), i can't investigate further (and anyway, it is of less importance right now). what's obvious now is that the 'idle' position of disc '4' dictates the correct exposure for a given shutter speed (with the rest of the variables known), in this case 1/1000s (required for the correct reassembly of the shutter sensing ring in respect to the shutter speed gears beneath the mirror). unfortunately there are no marks on disc '4', except for the place where the cord is glued in place. the problem is that i don't know where to align that mark. i thought perhaps it should point to 6 o'clock but the tensioning seems too low to compensate for the error i believe it has now. next option would be 3 o'clock but it might as well be any other value.
perhaps someone has some knowledge about it? |
Zenzaman
Tinkerer
Username: Zenzaman
Post Number: 7
Registered: 11-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, November 20, 2010 - 06:38 pm: |
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after a long process of trial and error i found a possible correct position of the control disc. the line of the string being glued to the disc should point at 6 o'clock when normally reassembling the camera (with the shutter speed set to 1/1000s). unfortunately this position is a bit hard to see and set accurately. by 'reverse engineering' i found that for 1/8s, the string glue should align with the lowest part of the body 're-enforcement' on the right side of the control disc (while facing the camera) - see the circled area in the picture. http://i187.photobucket.com/albums/x228/alinCiortea/camera%20repair/IMG_3565_.jp g
while in this position, the shutter sensing ring blocks access to one of the four screws of the aluminium frame surrounding the lens mount. i suggest the sensing ring is turned to its default 1/1000s position but attention must be paid while rotating the ring, otherwise the gears might slip and the correct position of the disc be lost.
i can only confirm that the readings now match those of the one remaining 'healthy' om1 i have, but i'll also do a test strip tomorrow. |
Zenzaman
Tinkerer
Username: Zenzaman
Post Number: 10
Registered: 11-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, November 21, 2010 - 08:39 am: |
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and this is the result, exposed according to the light meter reading> http://i187.photobucket.com/albums/x228/alinCiortea/camera%20repair/Untitled-10. jpg |
