On 2011-03-15, Ignoramus1540 wrote:
I have something that is a yellow steel box, called a civil defense
radiation detector.

http://www.radmeters4u.com/cdv715-new.jpg

I only have the yellow box.

No matter what I do, I cannot zero the thing. The needle goes all the
way to the right to Circuit Check. Does anyone know how to fix that.

I have one similar (somewhere), and IIRC there is a schematic on
the inside of the yellow box. Might help you to trace out the problem.
Could be a failed electrolytic capacitor somewhere in there.

I fully realize that the meter has an inappropriate range. So if you
feel like pointing it out, I know that already.

Inappropriate for what?

Granted, 500 mR/hr at the best seems to not be particularly
sensitive, but it is sufficient for its intended purpose.

IIRC, it also really wants a fresh zinc-carbon cell to power it
-- an alkaline cell is a bit low on voltage. (At least based on my
memory of the behavior of mine last time I dug it out.)

Enjoy,
DoN.

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