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

i

On 3/14/2011 9:42 PM, 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 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

--
www.wbnoble.com

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.

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.

http://www.vaughns-1-pagers.com/scie....htm#schematic


--Winston

Winston wrote:
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.

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.

http://www.vaughns-1-pagers.com/scie....htm#schematic

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

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

i

Does it have the separate probe and the little radioactive test patch
stuck to the side of the box?

On 2011-03-15, Pete C. wrote:

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

i

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

On Tue, 15 Mar 2011 07:21:27 -0600, "Pete C."
wrote:


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

i

Does it have the separate probe and the little radioactive test patch
stuck to the side of the box?

An op/maint manual for Ig, with schematics:
http://www.orau.org/ptp/Library/cdv/victor717-1.pdf

--
Small opportunities are often the beginning of great enterprises.
-- Demosthenes

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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