Nikon F Photomic Meter way off (i think?) with 1.5v batteries

Discussion in '35mm Cameras and Accessories' started by shootfilmto, Oct 8, 2017.

  1. E. von Hoegh

    E. von Hoegh Member

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    They show up pretty regularly for sale, cheap. Some will be ok, but many will have dead/dying Cds cells and/or bad resistors. Virtually all will need service of some sort, keep in mind that they are all getting close to 50 or more years of age. I have one good one which I use only for macro work where TTL metering is a real convenience. Now that I have a couple F2As, both with good meters, i guess it can die if it wants.:sad:
    Check Sover Wong's website, he may have some options. He's located in England.
     
  2. cooltouch

    cooltouch Member

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    I have successfully cut a slot in screws that I've managed to bugger up, a slot deep enough where I can use just a flat-bladed screwdriver to unscrew it. Just a thought -- if you can reach it, that might be an alternative for you.

    The proper screwdriver to use on all cameras is not a Phillips. It's called a "cross-point" (according to a camera repair teacher I had). It's easy to see the difference between a cross-point and a Phillips. A Phillips has a long pointy head, whereas the cross-point is more blunt. It's very easy to strip a camera screw's head if you try to use a Phillips on it. Typically the screwdrivers you get in those ubiquitous jewelers sets are cross points.
     
  3. Exopix

    Exopix Member

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    This screw was not Phillips or cross-point but a regular old slotted one.
    What tool do you use for cutting a new slot in damaged screws?
     
  4. E. von Hoegh

    E. von Hoegh Member

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    "Cross point" is a generic term there are JIS, Phillips, Reed & Prince, and maybe a DIN type. Japanese cameras with crosspoint screws use a JIS driver. I believe all Fs and finders use slotted screws, as do the first few years of F2s; they went to the JIS crosspoints in the 70s sometime.
     
  5. E. von Hoegh

    E. von Hoegh Member

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    A screw-slotting file. I don't think your screws are accessible this way. It's also possible to carve a slot with a graver.
     
  6. cooltouch

    cooltouch Member

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    What E. said. Problem with most cross-point screws is they're also countersunk. Getting down in there without buggering up everything else will be difficult. Honestly, I think your best bet if you want to do it yourself is to get a small drill and drill off the head. You can probably rob a screw off a parts camera. Surely you must have a parts camera laying around?
     
  7. E. von Hoegh

    E. von Hoegh Member

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    OK, if I were doing it I'd use about a #65 drill, which is .035" diameter, actually I'd measure one of the other screws and select a drill about .002" larger. I'd pip a starting spot in what's left of the screw with a sharp pointed graver, drill into the head until it was just free of the shank, cut a slot in the end of the screw stump, soak the screw with acetone for a while and turn it out with a screwdriver. Sounds simple, right? It's easy when you have the tools and the skills to use them, impossible when you don't. I've been working on tiny mechanisms - think watches, tiny watches when necessary, for going on 40 years One restoration job involved making a new escapement for a very small ca. 1800-1810 form watch with verge escapement. The escape wheel was .079" dia, of contrate form, and had 13 teeth. I also made the cutters to cut the wheel.
     
  8. Exopix

    Exopix Member

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    Thanks. I will try with a small drill. Let you know if it works.
     
  9. John Koehrer

    John Koehrer Subscriber

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    E's solution is also yours. But once the head is gone you should be able to pop the cover off. When it's off, grab the protruding bit with a pliers & unscrew it.
     
  10. Exopix

    Exopix Member

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    Managed to get away the damaged screw. Opened it and cleaned the ring resistor with isopropyl. Seems like it is less jumpy now and also more accurate; about 2-2,5 steps wrong instead of 5 steps. What about the trim potentiometer for the meter. Can I use that to compensate for the wrong meter level?
     
  11. E. von Hoegh

    E. von Hoegh Member

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    Nice! :smile: Could you tell precisely how?
     
  12. E. von Hoegh

    E. von Hoegh Member

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    Crosspoint screws. I was at a friend's house this morning and needed a pliers to do something, he gave me a cased set of miniature tools. In that set was a "0000 Phillips" screwdriver, upon inspection it turns out to be a JIS standard, definitely not Phillips. Interesting, perhaps purchased in bulk, labeled with what Americans are familiar with? I dunno. I tried it in the baseplate screws on my late F2, it fits perfectly.
     
  13. Exopix

    Exopix Member

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    Drilled away the screw.
    What do you say about the potentiometer?
     
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  15. E. von Hoegh

    E. von Hoegh Member

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    What size drill, and did you damage anything else?

    As for the resistor ring, I'd have to find the schematic of the meter and see what's going on. I don't remember with confidence if it is a potentiometer or a rheostat. Give me time, I'll respond.
     
  16. Exopix

    Exopix Member

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    I mean the trim potentiometer on the upper side of the meter head. There is one for adjusting the meter and one for the battery check.
     
  17. Exopix

    Exopix Member

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    Anybody know if it's possible to adjust the trim pot to compensate for the wrong meter level?
     
  18. E. von Hoegh

    E. von Hoegh Member

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    Which Photomic do you have?
    The trim pot will let you tweak it, I'm not sure if you'll get 2 or more stops with linearity though. The CDS cells age and lose linearity, in some (all?) Photomics there are two internal potentiometers to correct this, but beyond a certain point you'll need new cells.
     
  19. Exopix

    Exopix Member

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    It is a DP-1.
     
  20. E. von Hoegh

    E. von Hoegh Member

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    Ah. So it's an F2 not an F. There's a service manual on the web somewhere. The DP-11 is identical save for the aperture coupling mechanism.
     
  21. Exopix

    Exopix Member

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    Sorry, it's a Ftn meter for this Nikon F. I have a F2 as well and I mixed them up.
     
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