Sick Meter in FTN

[ColColt]

I've got a couple of Nikon FTN Photomic cameras. One with batteries works fine. The other has a dead meter. I mean deader than 4 o'clock. New batteries and the needle don't move. Ideas as to where the problem may lie? Something I can fix, perhaps?

 

[John Koehrer]

corroded wire, bad meter switch?
If the battery corroded at one time, the wire from the battery to the board may have internal corrosion.
Switch may be tarnished contacts,
Beyond that, meter cells, poor contact with wiper.

IF(!) I remember right there's a brass screw under the leatherette on top and four at the bottom, maybe covered with foam.

 

[ColColt]

The battery compartment is clean as a whistle. Meter cells are a probability. It seems many moons ago I tore down another FTN meter and cleaned the resistor ring on one that was reading erratic and that fixed that problem. with this one not even moving the needle I wasn't sure where to start. My little jeweler's screwdrivers have hid themselves somewhere here or I'd take it apart.

 

[Sirius Glass]

My first recommendation would have been to clean the electrical contacts and the battery compartment. Next you can either send it out or carefully tear each one down. You know this but for the other readers:

1. Store screws and parts in glass jars, preferably numbered. Put the tops on the jars that you are not using at the moment.
2. Take photographs of each step of the tear down. This is a good use for a digital camera.
3. Take notes.
4. Look for repair videos on u-tube.
5. Work over a hardwood or equivalent floor. Do not work over a carpeted floor.
6. Use a good electrical contact cleaner on soldered joints and mechanical electrical connections.

 

[ColColt]

I found an interesting sketch. I don't recall having to take the leather off the top of the meter on the one I worked on some 25 years ago but I've forgotten a lot of things from that time.

http://rick_oleson.tripod.com/ftn-1.jpg

 

[bsdunek]

I've had trouble with both the drum resistor and the switch contacts. A little cleaning with electronic cleaner seems to work most of the time. Worth a try, if you find your screwdrivers.
ColColt - useful sketch. Thanks!

Oh, forgot one thing. The spring at the bottom of the battery compartment. Rotate it out and clean the end of the spring and the metal it sits on. I've had this work too, even when there's no visible corrosion. We're talking very low voltage here - can't get through much dirt or corrosion.

 

[ColColt]

Here's another sketch that may help someone.

http://rick_oleson.tripod.com/ftn-2.gif

That's a good idea about taking the battery spring out...never thought about that since it all looked good.

I'm beginning to look at the Gossen DigiPro F2 meter as a digital backup. Anyone with experience on this meter?