Nikon F3HP - light meter malfunction

Discussion in 'Nikon' started by 10996697, Oct 28, 2020.

  1. Dear all,

    I hope I will find an answer in this community.
    Ive got a Nikon F3HP with problems.
    This is not the 1st time I am fixing a camera but now I cannot find the solution.

    I have checked:
    - all shutter speed are switchable and seems to be accurate
    - film counter works as it should: the 1st three shot are limited to 1/80 speed as in the manual written
    - FRE is cleaned. Wirings and solderings are OK. AI coupling from F-mount is OK, wire connection exists.
    - mirror mechanism and shutter OK

    Malfunction:

    - the light meter seems to be completely out of its order. In Auto mode in LCD is -8- visible. This values doesnt change if the light source is changing (from complete darknes thru lens cap thru pointing to harsh sky)
    - the -8- value stays if lens aperture is changed (from F1.8 - F22), no change in the metering read out
    - in Manual mode the shutter speeds are correctly displayed but the "-" sign is visible in every condition.

    Current situation: in the repair manual there is only one time mentioned this sympthom with checking the film counter. I dont know how to proceed further.

    Has anyone experience with this issue?

    Thanks in advance!
     
  2. Silly question - have you tried a new battery?

    I seem to remember that -8 on the LCD indicates a low battery.
     
  3. Hi,

    yes, I forgot to write: I have tried with 2 new sets of batteries (Varta and Duracell). Is there maybe a voltage leak or contact problem of the batteries?
     
  4. Contact problem between finder and body maybe?

    I'd clean every electrical contact you can reach without dismantling anything.
     
  5. Hmm, I think between body and finder are no any electric connection.

    After deeper cleaning of battery compartment and contacts the reaction of the light meter changed. Now it reacts on lightsource changing: the read oout values are variing between -1 (harsh sky) to -8 (darkness). But still not working correctly.

    Any new ideas?
     
  6. The photocell or the logarithmic amplifier is bad. The service manual shows you how to measure the voltage output of the amplifier.
     
  7. It's been a long time since I lifted the prism off my F3HP and I couldn't remember if there were any contacts or not.

    I did have second thoughts after I posted.

    Did you also clean the battery compartment cap? It forms part of the circuit.
     
  8. Can you maybe do me a favour and tell on wich page is the corresponding measure points and values?
     
  9. Yes, I have cleaned the screw-thred and the contacts as well.
    I think, I will try without batteries but direct DC 3V feed. Maybe she is sensible on the batteries...?
     
  10. Thank you all, but there is no further discussion necessary. I dismantled the FRE gear completely at now it is visible, that is cracked in 3 pieces.
     
  11. What a pity. Sorry to hear that.
    In case anyone else has the -8- display problem:
    Screenshot_2020-10-29-13-25-22.jpeg
    Screenshot_2020-10-29-13-29-17.jpeg
    I just hope this doesn't bring Nikon's legal team down on us!
     
  12. Page E16 describe the function of the meter.
     
  13. Silly question, but what's a FRE?
     
  14. mike_halliwell likes this.
  15. c_watson just answered that one. I guess when it breaks, it becomes an NFRE - a non-functional resistance element.
     
  16. I gotta say, that just a truly daft name for a thing....;)

    If you look at the close-up, it's more a multi-functional resistance element.
     
    Last edited: Oct 30, 2020
  17. Fragile resistor element!

    There was basically nothing wrong with a robust potentiometer, but oh no, Nikon just had to 'improve' on it with a biscuit of ceramic so thin that it breaks with a sneeze.
     
  18. But then I think there are 2 FRE's. One for the AI coupling and the other is for the ASA dial.
     
  19. Never had problems with this on two F3 bodies and two FEs. A Nikon.ca tech volunteered that it would take a strong, well-aimed punch to the top left dial to bust the FRE, not just a drop or rough handling. Only problem I ever encountered with an F3 was a fading LCD readout on an early model--an age-related issue. Complex ribbon circuit plus tiny LCD panel long out of stock. It's still readable but more like mid-gray on gray rather than black on gray on a late model body.
     
  20. Well you wouldn't with an FE, since it doesn't use an FRE.

    But just Google the number of F3 FRE breakages reported. They can't all have been thumped hard over the rewind knob.

    And remember that the F3 was introduced as Nikon's flagship professional model, it should have been designed to take a knock or two from the outset.

    Maybe the substrate of the FRE develops stress fractures over time? Whatever. It seems to be the Achilles heel of F3s.
     
    Last edited: Oct 31, 2020

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