Extech DC clamp meter, large DC offset developed.

** As the problem only affects the DC amps ranges, it might be the jaws or other parts of the magnetic circuit have become magnetised so offsetting the Hall Effect sensor.

Holding the meter near an analogue CRO screen will reveal if this is the case.

Otherwise the unit has developed a fault.

.... Phil

My DC clamp has the same problem. Got it used and it was that way from the start. I considered trying to demagnetize it, but fear the voltages induced by the attempt might bust something, so I just use the zero function. It takes a very small magnetic field to disrupt the zero. Unless the initial offset is 0.0, you have to zero it anyway.

I contacted the vendor and they said, "push the zero button."

I once had a DC clamp probe that zeroed itself every time you opened the jaws. Nice feature.

I would get inside and clean any range/function switch contacts. Does the manual advice against use near loudspeakers, laying meter jaws next to screwdrivers etc

You gave me an idea.. We have a demagnetizer in the shop.. I can stick the jaws in it and give it a shot.

Thanks..

Or get a Fluke. Odd things like this is why I won't touch B brands... I need to trust my gear and not f*ck around with crap.

this meter is only a few days old in my hands, there should be no crud in there. The manual only says to remove test leads when using the clamp and there is an obvious reason for that, to prevent the leads getting into the equipment while reaching in. The leads were still in the package.

I will try a demagnetizer/degaussing process

Jamie

Ok, we have flukes there too, they fail just as bad ;)

Jamie

case. "

Ha. Try finding one these days. I got a couple laying around not hooked up. Gave Ma one when her XBR took a shit and it is CRT. But I bet if I walked up and down the street and banged on people's door I would have to walk mil es before finding anyone with a CRT based TV.

Years ago people were already laughing saying "TVs are flat now, stupid".

So how do we indicate if something is magnetically charged with the lack of color CRTs or whatever ? I was thinking a guitar string but how do we know it itself is not magnetised ? I fit is used it has spent alot of time righ t in front of a pretty strong magnet. See if it attracts to other strings ? I guess that might work.

I think this guy needs to wrap wire around those jaws, and out of phase so they don't blow the thing out (or disconnect it) and just demagnetize it wi th a stepdown transformer to something reasonable so as not to blow the var iac either and give it a good douche of 50 or 60 Hz, depending. If the bogu s reading goes away we know what happened.

Now if it doesn't, the plot thickens.

I f***ed up the quoting on that.

Because now we have GPS no-one has a Boy Scout compass any more?

Mike.

** Most techs have one - I own four.

Analogue CROs are what we all used until DSOs with LCD screens came along.

The trace is very sensitive to a magnetic field.

.... Phil