Triplett 60 VOM Static Electricity Problem

[nsubulysses]

I got a Triplett 60 VOM which is kind of cool but unfortunately I'm realizing now that it has a serious ability to hold a static charge. I have a handful of other VOMs and have never encountered this the of thing before. Is it because of the plastic case material or is the meter damaged? Do I have to put a dryer sheet in the case or something@!!

In the manual it says the plastic window is a static dissipative material but that's not true anymore it seems.

[Leo_Gnardo]

Do I have to put a dryer sheet in the case or something@!! The manual it says the plastic window is a static dissipative material but that's not true anymore it seems.

You're on the right track. I'd wipe the inside and outside of the meter window with a dryer-sheet for a first attempt at beating static.

If that doesn't work next level is anti-static spray you can find in the grocery store. I've used Static Guard, the can has an orange lid. You won't need much, no need to hose down the gear like you're trying to spray paint it.

[nsubulysses]

You know, this is really weird. I calibrated this meter twice, or at least I tried, until I realized the reason it wasn't working is because the needle was under the influence!! So then I stopped trying to cal.

Thanks for you input Leo I will try the dryer sheet first and see what happens. Wondering why this is happening in the first place though? Will I have to de-static this meter every time I use it to make sure the display is accurate? Is this because the display window is plastic? I have Simpson 260 and a Triplett 630 and have never had this problem, but I think both of the display windows are actually glass.

[Jazz P Bass]

That plastic window is the cause.
Welcome to the world of static electricity.

[Tom Phillips]

The effect you show is really extreme and surprising. I understand the possible cause but there are many meters that use plastic housings that do not have the problem you show. Maybe they got a bad batch of meters made with incorrect plastic. I'm thinking that any application of anti-staic coating would only be a temporary fix. Maybe a conductive ground strip across the meter face would help. However, the meter should not have the problem you showed in the first place. When was that instrument manufactured?

[nsubulysses]

I know that this meter came out in 1975. Mine has a cal sticker for July 1987, so Id guess this meter is from the 70s, or the early 80s at the latest. I don't think it's a special version really, but it does have a Mining Enforcement and Administration Standards approval sticker. I don't think they all said that.

[g1]

From my experience, this condition is not necessarily something that was always there (defective material). It would seem this is a condition that can just occur. Whether due to changes in the plastic (break down?) or the accumulation of a static charge I do not know.
I have an old tach/dwell automotive meter that I used for many years, one day it just stopped working right and the needle would hardly move. After making sure it was not seized I realized it worked fine with the plastic window removed. I can't remember how I removed the charge, I don't think I used anti-stat, but the problem is no longer there.

[Tom Phillips]

I just tried the finger rub test on some ~50 year old equipment that use plastic case meters. I could see some slight detectable needle movement but nothing at all like that shown in the post #1 video. With my glass front analog meters there is no detectable meter needle movement during a finger rub test.

[km6xz]

Static Guard is one product that is available many places such as grocery stores and auto parts houses. The meter window had anti-static treatment at one time but wore off apparently. It gets worse when humidity is very low such as when there is very cold dry air. A humidifier helps everything from your nasal membranes to meter window. Spray the whole case, inside works well because the chemical does not wear off as quickly as when rubbed in daily use. That meter movement is probably a 50microammeter or even more sensitive so static will be more of a problem than a cheap 1ma movement., but the ohms'volt will be worse for loading as well with a lower sensitivity movement.

[Enzo]

Back when the old arcade games Galaxians and PacMan came out, the things were extremely static sensitive. We diluted some Downy fabric softener in a spray bottle, sprayed the carpet around them, problem solved. Similar carpet and laundry aanti-static products ought to help.

[Mick Bailey]

I used to see kids with piezo disposable lighters trying to get free games from arcade machines; they took the top off and sparked the electrode against the coin slot. Don't know if it ever worked though......

We used to have lots of problems with static. The ladies in a brand-new office complained of flea bites on their legs. I took a look (as I recall I had to look at lot - we needed to be certain, of course) and sure enough it looked like flea bites. We had pest control people spray the place and still a problem. I read somewhere about static problems with carpet tiles firing polyester needles into people's skin due to static. I got some anti-static spray and one evening went over the entire floor. Problem solved.

[nsubulysses]

I have I have been sidetracked by other things but I will definitely be buying some static guard for this meter. It is fully functional and easy to calibrate. Would be a nice little addition to the test equipment stash. thanks everyone

[J M Fahey]

Ouch!!
Never ever saw anything like that,and I've owned some real cheap multimeters.

But I'm quite certain that:

but it does have a Mining Enforcement and Administration Standards approval sticker. I don't think they all said that.

definitely is a clue.

Just yesterday I was reading a Soviet era mining book (fascinating) , and among other things, they are obsessive (for good reason) about electrical installations, static electricity, non sparking tools, etc.

The reason?
Rocks in some mines, specially coal ones, exhale methane gas ...... a.k.a "natural gas" .
Now you know what happens when you are in an enclosed space filled with air/gas mixture and the tiniest spark flies.
Why Do Coal Mines Explode?

I have seen electrical motors, electrical switching panels, relays and contactors, etc. "approved for use in explosive gas atmospheres" so this meter is different to others.

How?
Don't know, but definitely that's no plain vanilla meter.

Statistics mentioned above are chilling:
* methane/air mixture is explosive between 5% and 15% mix.
* "In most U.S. coal mines, each ton of coal contains between 100 to 600 cubic feet (2.83 to 17 cubic meters) of methane,"
that's incredible, now I think of coal as a loaded gas tank beink punched with pickaxes !!!
*

Since 1839, there have been 501 known U.S. coal mine explosions that killed at least five people each, according to the National Institute for Occupational Safety and Health. In addition, at least 52 coal mine fires have killed at least five people each. The worst of these disasters was an explosion that killed 362 people in a coal mine in Monongah, W.Va in 1907.

Boy, that's not a plain meter by any means.

[km6xz]

Juan, whether it was approved for explosive atmospheres or just for use by the agency depends on the class of approval. Just think our new congress has put getting rid of all those pesky safety regulations because they say they impede businesses from making maximum profits. They already approved a number of years ago, waivers for coal mine owners from being held liable for damage done during mine disasters. The US is heading right back to 1898 just before the first real regulations went into effect.

Just as destructive are dust explosions such as in grain elevators or milling facilities. Just about anything milled fine enough from aluminum to wheat will blow up a good sized town. Regulations only came into various fields when major disasters occurred often enough to generate enough anger among people to overcome the resistance by business owners who were dead set against any safety regulations.