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Olympus OM1n battery

Discussion in 'Classic Models & Marques' started by Ian51, Dec 22, 2015.

  1. Ian51

    Ian51 New Member

    Hey all

    I have recently purchased my as new OM1n and although the lens that came with it is a bit rough the body is as described. Mint+++

    So it came with a PX625 battery and I switched on the meter which sprung to life. The battery is a 1.5v so I am aware that I need the CRIS convertor to use a 1.3v silver battery for correct exposure. The needle was jittery and swung violently on occasions so rather than delve into the depths and start checking wiring and terminal etc. I thought I would try a commonly substituted hearing aid battery just to rule out the possibly dodgy battery that might have come with the camera.

    So heres the thing. I put a 1.5v hearing aid battery in and once again the meter swung into life and seemed steady. That was enough for me to go ahead and order the proper battery convertor from ebay. I turned off the meter and the meter was still metering and reacting to both aperture and speed settings. I took the battery out and it is still metering and reacting to changes in settings.

    Does anyone know if a charge is held in the meter for a while. I have left it half an hour and it is still metering. I was expecting the meter to immediately switch off but it has not done. It did switch on and off with the first battery so how comes it is still metering without a battery.

    Imagine if I had a fully functioning meter OM1n which didn't need batteries. How cool but also how impossible.:)

    Any ideas folks??
  2. Ian51

    Ian51 New Member

    No problems all sorted false alarm :D
  3. Trannifan

    Trannifan Well-Known Member

    The exposure meter circuit seems to be a weak point in the OM1n. Years ago I inherited an OM1n from my father. One day the meter just packed up and a new battery didn't bring any life to it. Down at the local camera shop the reaction was, "Ah yes, we know about this problem......."

  4. Ian51

    Ian51 New Member

    Hi Lynn

    Thank you for the reply. For some strange reason it seems to have rectified itself and the meter is working fine. I doesn't explain how a meter could work without a battery but it works so I can go out and take some pictures.

  5. jchrisc

    jchrisc Well-Known Member

    I used an OM1n for a long time but memory fades. I'm pretty sure however that it used a 1.3v Mercury battery and it was the banning of Mercury that brought the need for adapters. When the battery ran down, the only thing that stopped working was the meter. It's difficult to understand how it would meter without a battery. In its later life I used the camera a lot with a hand-held meter.
  6. Trannifan

    Trannifan Well-Known Member

    According to the OM-1 instruction manual, the required battery is a PX625 1.35V mercury battery. "Alkaline batteries (LR44, A76 etc.) may not be used."

  7. Ian51

    Ian51 New Member

    Hi there Lynn

    Thank you for the reply. I have ordered a small battery adaptor which allows the new silver 1.5v batteries to be used it adapts the size to the PX625 and also reduces the voltage down to 1.35v so I think I've sorted it. I just need to win the lottery so I can buy a 50mm f1.2 lens and a 24mm f2.8 tee hee :)

  8. Olyfix

    Olyfix New Member

    I realize this is an old post, but for informational purposes I reply.

    On the OM-1 and OM-1n cameras, it is possible to mechanically position the meter so that, even "off" or without power, the needle deflects off the lower stop. In other words, it may appear that you have set the needle within the bracket for an accurate exposure (using the "B" or an extremely low shutter speed setting along with a wide open or near wide open lens aperture), but you will note that the needle does not react to changes in light. (The very, very earliest OM-1 cameras were built with circuitry to deflect the needle in this event (presuming the camera has power), but this was deemed unnecessary and discontinued quite early on.)

    The trick is to first check voltage on your battery. If it's "good" (1.35 volts or so), install it and, with the camera set to a lower speed and open aperture in bright light, watch as you switch the camera on and off. The needle should deflect. If it does not, you likely have a problem. Depending on the internal version and other factors, the battery lead (brown) and it's connection to the battery terminal may have corroded (quite a typical malady), or the meter's ground may be faulty. If the meter is "jumpy", it could be poor ground, a pinched or broken battery lead (brown wire) or a pinched or broken galvanometer wire (blue). After that, the causes become more and more unusual, and the skill of an experienced Olympus repair tech are in order.
  9. John Farrell

    John Farrell Well-Known Member

    A friend had an OM-1n, on which the insulation between the battery contact and its securing screw had broken down, grounding the battery. I replaced the metal screw with a nylon one, after recutting the the screw thread with an M2.3 x .4 die.
  10. Olyfix

    Olyfix New Member

    Ah, yes! At first, Olympus used a 1.7mm steel screw with a plastic insulator to hold the battery terminal in place, but switched to a 2mm hard plastic screw. Precisely when they switched over I don't recall, but the plastic screws began to break in droves! The plastic screws are no longer available (of course!), but fortunately, you can find slightly larger nylon screws in english dimension that do a fabulous job. The hole tapped in the body effectively cuts it's own threads on the nylon screw, and once screwed snugly in place, you simply slice off the end sticking up into the film take-up chamber with a small blade. Presto, fixed!

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