Olympus OM-1n battery compartment

Discussion in 'Classic Manual Cameras' started by davidsimon, Jan 9, 2018.

  1. I just bought a rather splendid OM-1n off the 'bay and it came with this rather nifty replacement battery compartment pre-installed, which is perfectly sized for a pair of SR44W's, and also swaps the battery terminal to the opposite side for easy installation of the required voltage dropping diode. Does anyone recognise this new compartment and advise where I can get more of them? Perhaps it's been cannibalized from a different camera, I'm not sure. Its the neatest upgrade I've seen so far on one of these lovely cameras.

    20180109_150441.jpg
     
  2. It looks like from the OM-2. The OM-2 uses 2 LR-44 batteries and I guess Olympus didn't want to redesign the battery compartment completely.
     
  3. An unmodified OM1 was designed for a single 1.35V mercury battery. The modification appears to call for two 1.5V batteries. Just saying.
     
  4. I have a couple of OM-1n(s) at home and an OM-2n. Offhand it does look very much like an OM-2n battery holder and it definitely takes two batteries as opposed to one.

    Maybe the intent was to shove a piece of foil (or something) in there along with a single battery?

    On the other hand that's a more substantial diode than I'm used to seeing for this type of modification but I can't see it dropping the voltage 1.5+ volts.
     
    Last edited: Jan 10, 2018
  5. After pulling the bottom plate on my OM-2 I'd say what you have there is actually an OM-2 rather than an OM-1. Is there a small circuit board with an IC on it at the opposite end from the battery holder? If so, it's not an OM-1 you've got. Did somebody switch the top plate?
     
  6. Here are the true baseplate differences between an OM2 & OM1n..
    P1010741.JPG
    Bottom is the OM2
     
  7. I can see only two differences between the OM-1 and OM-2 in the above photo. The battery compartment, and the presence of the purple wire in the OM-1n and the black wire plus diode in the OM-2. Please note that in the top photo, showing the OM-1n with the OM-2 style battery compartment that it still has the purple wire, plus the addition of the black wire and diode. And that diode looks to be the same as the one used in the OM-2.

    The biggest question I would have is, is the OM-1n giving the correct exposure values when batteries are installed? If so, then that diode is doing its job. If not, then perhaps a 675 hearing aid battery and a wad of foil is called for (although the diode may drop its voltage). A 675 should fit that compartment just fine. The 675 hearing aid battery delivers 1.4v compared to the original mercury's 1.35v. Close enough, I've found. True, 675 hearing aid batteries don't last very long -- maybe two or three months -- but they're so plentiful and cheap that it is almost worth it to install a new one at the beginning of a new shoot. I buy my 675s at Costco. A card of 48 for less than $10.

    Having said all that though, first give it a try with a couple of 1.5v batteries and see how it performs.
     
  8. Still think it's a case of mistaken identity. Below is a picture of the bottom of an OM-1n (left) next to an OM-2n right). I'm surprised the 2n has a circuit board and a 2 does not, but anyway you can see that the 2n battery compartment area looks exactly the same as the OP's, purple wire, diode and all.

    What the OP appears to have is not a modified 1n but a stock 2n.

    [​IMG]
     
  9. Hang on a minute -- if the OP's OM-1n is actually an OM-2n, as you claim, then what happened to the integrated circuit and all its accompanying wiring in his camera, as is shown in the OM-2n in your photo? Also, there are a few levers shared by both OM-1s that are not shared by both OM-2s (but the OM-2s share their own levers). Check out the lever arrangement to the left of the tripod mounts in the top photo and north of the tripod mounts in the bottom photo. No, that camera in the very top photo is definitely an OM-1, whether an "N" or not, I can't say. But it's not an OM-2.
     
  10. It probably would have been better if I had oriented my cameras with the battery compartments up as in the first photo. You don't see the circuit board in the OP's photo because it's at the other end (if it is an OM-2n). The levers north of the tripod mount in my photos aren't visible in the OP's photo so there isn't a way to know if they're the same or not.

    There is definitely a difference in the levers between OM-1s and 2s on the side of the tripod mount away from the battery, but they look identical on the other side, at least to me.

    I suppose it's possible that somebody took a battery holder from an OM-2n and plunked it in an OM-1n, but why? It doesn't solve the problem. Or more accurately, it solves one problem in terms of battery fit, but creates another. And it doesn't address the voltage issue at all.

    It also seems telling that we haven't heard from the OP. Maybe the top plates weren't switched. Maybe he just got an OM-2n instead of what he expected and didn't really look.
     
  11. Sorry, I was referencing the bottom two photos only and had forgotten about that top photo. Yes, now looking at the OP's photo, it seems as if it could be an OM-2N. We'd need to see more of that camera's base area before we'd know for sure.

    I agree that, if the battery compartment were just plunked in, even with the diode, this doesn't resolve the voltage difference.
     
  12. Well, with batteries removed try the shutter. If it fires at all speeds without batteries then it cannot be an OM-2.
     
  13. Perhaps it's an OM10 ....
     
  14. I doubt that. The OM-10 is too wimpy.
     

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