Selenium cell meter needs a kick-start

Kirks518 · May 11, 2015

I picked up a really cheap Canon Demi S that wasn't working (stuck shutter, and the camera looked rough and dirty). I got the shutter working again (crazy easy fix), and cleaned it up nicely, and all seems to be working fine (inaugural roll is in it now).

The only issue I'm having now is with the meter. It's testing as pretty accurate (as accurate as a selenium meter can be I guess), but when I first take the camera out of it's case, the needle is 'stuck' at the 'no light measured' setting. If I cover the meter window with my finger briefly, then remove my finger, the needle jumps to life, and measures just fine. Any idea what's causing this, and should I bother opening it up to try and improve it? If it's something as simple as applying some electrical contact cleaner, then I'll do it, but if wiring or circuitry is the probable culprit, I'll leave it alone.

Kirks518 · May 11, 2015

^works for me!

Xmas · May 11, 2015

Contax III meters had the same syndrome from new.

Bought a very early collector Kiev clone from dealer with the same 'fault ' well cheap.

Yours could be similar but even if not aerosol or tinkering very likely to kill.

The selenium meters were very accurate but prone to moisture ingress or continamation of contacts, wait till it stops reading.

Sirius Glass · May 11, 2015

Selenium and CdS cells need time to start up. That is normal. See articles in the 1960s in Popular Photography and Modern Photography.

DWThomas · May 11, 2015

Are you actually applying any pressure with the finger? Back in the late Jurassic period I bought a Waltz Coronet that was a selenium cell, no battery meter (and all I could afford). After a year or two, when I would get it out it would typically not give a reading. I would then push in on the clear plastic honeycomb over the cell in the front and -- boing! -- the needle would spring to a reading. The connections on the early selenium cells were generally just pressure contacts, no actual permanently attached wires. As such they were prone to contact contamination as Xmas mentions. I still have the meter for amusement and have not recently tried it, but years back, flaky as it sounds, I found it either read correctly or it didn't read, so it was "reliable" in an odd sort of way!

IloveTLRs · May 12, 2015

I have a Pen FT that acts similarly. The meter needle gets stuck in the over/under area. A few taps and it gets unstuck. A fix would be nice.

Kirks518 · May 13, 2015

I've been noticing now that the camera is seeing some use, and isn't in it's case for more then 24 hours, the needle is just acting like it should. It's coming out of the gate without me doing anything, so I guess it just needed some use.

Xmas · May 13, 2015

Well done.

The little galvanometers are very difficult to address and need non magnetic tools...

paul ron · May 18, 2015

Lots of old meters suffer from sticky needle rubber bumpers and in some cameras, light seals get gummy n drippy into the works.

The cds cells do need time in the daylight to get their vision back... Sometimes, not always. They deteriorate at the wire connectors, lead solder powdering syndrom.

Selenium cell meter needs a kick-start

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