On Jun 19, 8:38*pm, "Shaun" wrote:
"Dave M" wrote in message

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wrote in message
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I picked up this probe at a yard sale for 5.00. After cleaning up the
connectors and installing a new AAA battery it works on resistance and
voltage ranges with the accessory cables supplied but when clamped
around a current carrying conductor it reads zero. I'm guessing that
there must be some kind of coil wrapped around the jaws internally on
this thing in some way. Current flowing through a conductor would
induce a voltage into this "primary" with a "secondary" connected to
the meter. I'm guessing here. I'm not really sure what is inside of
this meter. Can anyone tell me something about the theory of this type
of instrument and if they have any experience with this model. I may
have to get inside and would really appreciate some help with that as
well. There doesn't seem to be an easy way to do that without a
special tool. The company was no help at all.Thanks, Lenny.

I'll bet that you clamped the current jaws around a 2 or 3 conductor cord,
right? *If so, your meter will read zero all day, no mater how much
current you have in the wires. *Oh, and it must be AC current; it won't
work on DC.
The reason that the meter won't work if clamped around both conductors in
the cord is that the fields created by the current cancel each other.
You'll have to split the cord so that the clamp only has one of the
conductors inside. *Then, it should work as advertised (assuming that
nothing is defective in the meter).
I recommend the line splitter at
http://www.licensedelectrician.com/Store/AM/ELS2A.htm. *It will allow you
to check current on an appliance without having to split the cord open to
isolate the conductors.

You can download a copy of the manual for your meter from
http://www.amprobe.com/manuals/RS3.pdf

Cheers!!! * Great find!!!
--
Dave M
masondg44 at comcast dot net

If that doesn't do it, open up the meter and look for two small diodes
connected to the pickup coil on the clamp and check them with a multimeter,
they often fail when someone puts too much current through it.

Shaun- Hide quoted text -

- Show quoted text -

I went back and read my post because I thought that I was very
explicit when I said that I "clamped it around a current carrying
conductor", meaning one side of the line. I suppose that I should have
said that. The diodes sound like a great idea to look into however to
open this thing it looks like there are two hex nuts surrounded by a
thick sort of plastic shoulder which makes it impossible to get a
socket on to. Any ideas? Thanks, Lenny.