I have something that is a yellow steel box, called a civil defense radiation detector.
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 fully realize that the meter has an inappropriate range. So if you feel like pointing it out, I know that already.
i
the detection tubes in these things have a limited life - look up the tube number and see what that tells you
Compare the voltage readings of your unit to what you see in this schematic. Preliminarily, it looks like a switch problem because the amplifier tube, V1 grid appears to be floating up when it should be grounded with 'zero' selected.
Connect your negative meter probe to the negative battery connector, not to ground.
--Winston
Evacuate?
LOL You are too far north of the jet stream Ig.
In the Troubleshooting section of the manual it says that "METER WILL NOT ZERO" [They are shouting, not me.] (Reads Upscale)
Tube Defective Improper Grid Bias or Plate Voltage
--Winston
Does it have the separate probe and the little radioactive test patch stuck to the side of the box?
Nope, it does not. I think that it is a POS, I will sell it on craigslist with full disclosure.
i
An op/maint manual for Ig, with schematics:
-- Small opportunities are often the beginning of great enterprises. -- Demosthenes
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.
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.
PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.