Sperry analog multimeter

ldj · Nov 19, 2018

My meter glass (plastic) got so bad I couldn't read it any more. I cut the center out and cut out a piece of plexiglass to lay over it. When I lay the new plexiglass over it the needle deflects nearly half way over. It is so much the adjustment won't bring it back to 0. The piece I cut out I can lay back over and needle doesn't move, Why? I thought it might be static electricity since I rubbed and polished it up. Then I rubbed the old piece and it still doesn't make the needle move. It's a puzzle to me.

Steve@Advance · Nov 19, 2018

I suspect static.

I used to run a hammer mill grinder. It had an analog load meter with a home made plexiglass (I assume) cover.

I could wipe the dust off with a rag and make the needle go crazy! Wipe it one way it would go up, the other way it would go down.

Probably something about the original cover, a different type plastic, that made it anti static.

Mutt and Jeff · Nov 19, 2018

static
click here

tech4 · Nov 19, 2018

That is a common problem with plastic face meters. If you do nothing, it will eventually drop to zero. You can mix a small amount of dishwashing soap and water and lightly coat the face. You need to let it dry and not rub the face. When it dries the soap will prevent static on the face.

jeffcat · Nov 19, 2018

Only way to really cure it is to have a glass replacement cut for it.
Plastic can hold an unbeleavable amount of static charge.

ldj · Nov 19, 2018

(quoted from post at 18:23:23 11/19/18) Only way to really cure it is to have a glass replacement cut for it.
Plastic can hold an unbeleavable amount of static charge.

Well I just went and looked and the needle has gone back where it belongs. I am going to go ahead and glue it down to the outside part I left. I did wet it with soap and it is drying now. If it does get static again I suppose it will be ok again after a little while. If I want to use it before it becomes OK is there a way to discharge it? I do believe this is the craziest thing I have heard of.

tech4 · Nov 19, 2018

You can usually put it on the lowest ohms scale and short the leads together to put maximum current through the meter and it will drop back down to zero. Depending on the meter movement, you can also put on a current scale and touch the leads together and it will drain the static charge. Just keep your hands off the face and don't rub with a cloth and it should be ok. Some of the more expensive meters have a transit position that puts a short across the meter movement to prevent static electricity from moving the movement. Many of the old Heathkit meters had a plastic face and static was a common problem.

caterpillar guy · Nov 21, 2018

If you glue it with silicone sealer it will be easier to remove next time for the same problem yellowing.

Texasmark1 · Nov 22, 2018

I'll go with static electricity from your polishing the face before installing. www static electricity and prevention and solve your problem.

Sperry analog multimeter

ldj

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Steve@Advance

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Mutt and Jeff

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tech4

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jeffcat

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ldj

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tech4

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caterpillar guy

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Texasmark1

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