VOM going crazy need help please

[Harold in CR]

YES, I did check batteries with another VOM. They read 1.56 and 1.57V. Takes 2--AAA batteries.

Tried to get V on a 72V pack and it read 99.86 dropping slowly to 96.23. Other VOM says 71.3V. I have 2 rechargeable NiMh getting topped off as I write this. Then, I can see if that reads correctly.

If this doesn't work, how can I check to see maybe needs recalibrating, etc.??

This is an E Tek brand VOM, paid about $45.00 or so. It's not a $200.00 Fluke, but, was working great for over 2 years, then, just started acting up ?

 

[amberwolf]

Mmm..remember that NiMH batteries don't reach as high a voltage as alkaline, so if the meter uses them as a reference or it's internal reference depends on them being a high enough voltage, the meter will read incorrectly with NiMH if it was designed for alkaline.


Also, when reading the batteries in the crazy VOM with a different VOM, were they still installed in the crazy VOM? If not, and were just loose, they have no load on them and could read higher than they really are.


Also, use the test leads off the "known good" VOM on the crazy one, and vice-versa, to see if it's a connection problem inside them.

 

[John in CR]

I bet it's just the batteries, since it's been working fine for a few years. The voltage probably sags when you turn it on. My camera reports low or dead battery once alkaline batteries get to around 1.5V

 

[Harold in CR]

Well, changed the batteries, No go. Swapped the leads for another set that worked well, no go. Checked the NiMh batteries for voltage. Full charge, no go. Left the VOM on the computer desk all day. Left the NiMh batteries in the crazy VOM.


Around 4:15 this afternoon, picked up the crazy VOM, turned it on, and the numbers settled to Zero as they should. Did a Ohms test, zeroed as it should. Checked the Alkaline batteries that I took out, still read 1.54 and 1.56. Took the crazy VOM to the shop and checked some batteries I was balancing, all checked out, comparing the readings to the good VOM.

This thing acts like a capacitor needs to charge before it reads correctly ?? Never acted that way previously ??

Damned if I know what is going on. Thanks AW and John for responding to this thread.

Harold in CR