Pentax MX Exposure Meter Not Functioning

Discussion in 'Pentax' started by bruce_varner|3, Sep 19, 2017.

  1. Hi,
    I have acquired a Pentax MX. It is in near perfect condition. Problem is that the light meter is dead, totally. I have tried:

    1) No corrosion in the batter compartment
    2) Contacts look good
    3) Using 2 A76 batteries
    4) Tried different batteries
    5) Inserted batteries both ways
    6) I do have the film winding lever out the 20 degrees necessary to operate the meter
    7) I am pressing the shutter release down 1/2 way

    I need some suggestions for obvious possibilities. I have repaired many cameras, just not that familiar with Pentax and want some likely possibilities before I tear the whole thing apart. Thanks!
  2. AJG


    Unfortunately, I think you have covered all of the obvious possibilities. I owned 5 of these at one point, which worked well for a long time. On one of them, the meter died after having first had lot of flickering of the LEDs in the meter readout. Fixing it required replacing most of the metering system, about $150 back in the late 1980's, so I suspect that you may need to do that. Where you would get those parts now is the question, and I doubt that you could find any new ones. One last thing: I always used silver oxide batteries in my MXs, not alkaline. They lasted a lot longer, worked better in cold weather and had a more reliable voltage drop off over time. I doubt that your batteries are the problem, but this would be a relatively cheap experiment.
  3. Thanks! Yes I have tried several different batteries/types. Have even used a tester to ensure that the batteries were up to snuff. Oh well. Guess I will save it as a parts camera in case I come across another MX.
  4. Sometimes the wire from under the battery tray corrodes through. I've not done this on an MX but on some Pentaxes you can remove the battery tray to check, by releasing 3 screws - after removing the baseplate of course.
  5. go here: Before doing the adjustment, try cleaning the contacts w/a small piece of paper towel w/a drop or 2 of lighter fluid in case dirt or corrosion is the problem. Conversely, if the meter is always on, bend the top contact up slightly.
  6. SOLVED !!!

    I have solved my meter problem. Thought I would pass along the solution. I really did not solve this myself but rather found the solution online. Instead of repeating it here, I have provided the link below. This was exactly the problem, and following the instructions resolved the issue!

    Pentax MX Meter Fix
    Last edited: Sep 23, 2017
  7. Thanks for sharing this Bruce.
  8. Useful link. My MX meter works, but the LEDs are very dim even with fresh batteries.

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