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Will_inoue
Tinkerer
Username: Will_inoue
Post Number: 18
Registered: 06-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, July 28, 2010 - 10:56 pm: | 
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Hi all,
I am working on an Olympus OM-1 that has a dead meter. I took the top cover off and found a loose blue wire that was disconnected from I assume the galvanometer. But I can't find the attachment point. Where does this blue wire solder to? There is a metal hook-like spot on the galvanometer with Pliobond residue nearby - maybe for strapping it down? Any help would be greatly appreciated. See attached photo. Thanks. -Will |
Olympfix
Tinkerer
Username: Olympfix
Post Number: 28
Registered: 05-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, July 29, 2010 - 07:14 am: |
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It goes inside the meter through the hole to the meter coil, held by a "lug" on the outside casing of the meter. . You'll have to remove the meter, but watch out you don't remove the meter from the housing. If you do, it's a tricky job to get the meter back to the correct position. Also, be aware of the correct timing between the gears on the base of the meter. Also, be careful not to bend the meter needle when removing the meter. While at it, clean the copper strip connecting the mater housing with the body (Earth) both sides and don't over-tighten the screw on reassembly. |
Don
Tinkerer
Username: Don
Post Number: 54
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, July 29, 2010 - 07:30 am: |
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It looks like the wire came broke loose from the galvanometer (the other end is soldered to the circuit bd. on the rewnd side). If so, strip a bit of insulation away to reattach it. I'm not sure of how it attached originally -- solder or maybe the hook like spot made a mechanical connection by pressing onto the bare wire but as far as I can see, it looks to be mech. If theres a small bit of solder near the hook, then it was soldered. Use a a low wattage iron (15 watt or so)to tin the end of the wire 1st. Olympus used pliobond to hold the wires in place. Be sure to leave enuf slack so the wire can flex w/the rotation of the meter. |
Will_inoue
Tinkerer
Username: Will_inoue
Post Number: 19
Registered: 06-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, July 29, 2010 - 10:44 am: |
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Thanks Don, Olympfix.
Olympfix, where is the hole you mention? Is it the squarish opening below the bit I'm calling the "strap" in the picture? Does the wire go behind the strap (tacked w/Plio), then down and through that opening to coil?
Also it seems there are two ways to remove/disassemble the meter. Do I remove the 2 larger philips screws on top by the copper ground strap OR remove the two philips screws underneath by the big cable pulley? Either way it looks like the gear set or the ISO/ASA mechanism will come loose and could be tricky. Any pictures? :-D THANKS. |
Olympfix
Tinkerer
Username: Olympfix
Post Number: 29
Registered: 05-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, July 30, 2010 - 11:45 pm: |
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Hi, Will, .Yes, that's the hole.As Don says, leave enough slack for the meter to go back and forth as the shutter speed/aperture changes and rotates the meter in the housing. No pix , sorry, -all my junk OM-1s have been raided for their meters, and none now available anywhere. I've been out of professional Olympus repairs for eight years now, and don't do that many any more. Check to confirm continuity of brown wire from the battery housing to the top left board... wire has a habit of corroding at the battery housing end, (also insulation screw breaks.), and is best replaced in full, which involves pulling the mirror box out...quite easy, but watch to get correct timing on speed ring when re-docking, and self timer actuator lever above shutter release bar link on reassembly. Most common problem with OM1s is meter, and 10% will be dead/open, most of the rest will be broken/displaced cords.. Only way to check continuity is to test earth (housing) with the point to which you're trying to attach blue wire on meter galvanometer. Very hard to explain meter reassembly- it involves "winding up " the spring loaded base ring with cord attached, and also having the teeth on the gears meshed correctly. Twenty years practice helps. Take copious notes, and photos, and lots of luck. |
Will_inoue
Tinkerer
Username: Will_inoue
Post Number: 20
Registered: 06-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, July 31, 2010 - 10:26 pm: |
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Olympfix,
Thanks for your help. I got the camera meter working again. Now that I understand the process and how things are functioning in there, the next one *should* go a lot smoother :-)
There are still a couple small issues. The camera meter is about 1/2 stop off and overexposing. And the meter needle sometimes hangs just above the "+" sign.
On the meter needle issue, I don't know what it is hanging up on. But while working on this, I did accidentally twang the meter needle - so maybe I did this, but it seemed to move smoothly before reassembly and I see no obstruction. The more inertia the needle has the less it occurs. (Is it possible for the needle to rub on the prism?) But overall this is pretty minor really, so I will use and enjoy it as is for now.
Thanks again. -Will |
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