Rehab Selenium Meter

George Mann · Mar 15, 2018

Hi guys. I just purchased a Beauty LightOmatic rangefinder. It has a selenium meter on the front of it that only just responds to light.

I am hoping to restore at least a limited range of sensitivity by removing as much oxidization from it as possible.

Anyone have any success stories that they would like to share?

paul ron · Mar 15, 2018

there have been many threads here about replacing the cells... mostly westons but im sure there must be a cell comparable to yours.

E. von Hoegh · Mar 15, 2018

George Mann said:
Hi guys. I just purchased a Beauty LightOmatic rangefinder. It has a selenium meter on the front of it that only just responds to light.

I am hoping to restore at least a limited range of sensitivity by removing as much oxidization from it as possible.

Anyone have any success stories that they would like to share?

Clean the contact surfaces between the cell and the rest of the wiring.
Good luck.

George Mann · Mar 15, 2018

I am looking to clean or rebuild the cell itself as well.

George Mann · Mar 15, 2018

paul ron said:
there have been many threads here about replacing the cells... mostly westons but im sure there must be a cell comparable to yours.

Any sources for the selenium cells?

E. von Hoegh · Mar 15, 2018

George Mann said:
I am looking to clean the cell itself as well.

No. Just throw it away if you're going to do that, you'll save some effort.
The contacts will be the rear metal of the cell, and a contact area on the perimeter of the front, usually looks like a thin bead of solder. Don't touch anything else, you'll only fu@k it up.

George Mann · Mar 15, 2018

E. von Hoegh said:
No. Just throw it away if you're going to do that, you'll save some effort.
The contacts will be the rear metal of the cell, and a contact area on the perimeter of the front, usually looks like a thin bead of solder. Don't touch anything else, you'll only fu@k it up.

I was able to clean one in the past. What should I look out for when doing so?

E. von Hoegh · Mar 15, 2018

George Mann said:
I was able to clean one in the past. What should I look out for when doing so?

What I just said. Do not touch the face of the cell.

George Mann · Mar 15, 2018

E. von Hoegh said:
What I just said. Do not touch the face of the cell.

What is the danger in doing so?

E. von Hoegh · Mar 15, 2018

George Mann said:
What is the danger in doing so?

You will damage (what is left of the) conductive metallic film which was vaporised onto the face of the cell.

George Mann · Mar 15, 2018

Does anyone still make these photocells?

btaylor · Mar 15, 2018

I don't think there are any replacements available anymore. Much of the time the problems are at the connections (resistance). Carefully clean the connections and you might have success. I was able to do that with an apparently dead Weston meter. It came back to life and even appears to be accurate. Might as well take it apart and try! otherwise it's only a conversation piece.

jim10219 · Mar 15, 2018

You might could find another meter with a good selenium cell and replace it with that. Or you could replace the selenium cell with a silicon one. Then you’ll have to add a resistor to compensate for the increased voltage, or use some kind of filter over the sensor to drop the light. Finding the right value or resistor or right strength of filter will take some trial an error, and it probably won’t ever be as accurate across the entire range as it was when new. Or you could wire in a cds cell and the appropriate battery and additional circuitry, if there’s room for all of that. But that wouldn’t be a simple task.

I have a couple of selenium meters. They’re all still pretty useful, so long as you remember to drop the ISO one stop to compensate for their decreased sensitivity.

Rehab Selenium Meter

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