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Sticky meter movement.

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3v0

Coop Build Coordinator
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I have an old sun auto tuneup kit form the late 70's.

Some years ago the analog tach movement became jerky. I am thinking either the bearing for the indicator needle is either dirty or the lube has dried up.

I am thinking of cleaning the movement with quick dry electronics cleaner from the auto parts place. Methane, n-Hexane, Isohexane and some petroleum distilate. Claims no residue.

Has anyone ever cleaned or lubed a an analog meter ?

3v0
 
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duffy

Well-Known Member
No, but I've adjusted a few. The D'Arsonval movement is usually sealed and doesn't get dirty. Jerky motion often results after the needle gets slammed from too much current, or dropped on the floor.

There's screw covers over the needle bearings, loosen them a little (half a turn, it falls out easy) and see if that helps. There's 2 spiral springs on the front and back that carry current, they are incredibly delicate and get bent easy, see if the coils are bent.
 

Leftyretro

New Member
Also I seem to recall static electricity build-up can cause sticking and erratic meter behavior. I forget the method to discharge the static but maybe a search will turn up something.

Lefty
 

3v0

Coop Build Coordinator
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I tried the tach today and it works fine as is.

The last time I tried to use it this was not the case. Maybe it was static as lefty said. Maybe the car had some strange problem or perhaps it is just teasing me :(

Not often you put broken things into storage and they come out working. I hope it lasts. :)

EDIT: This time I was working on a 4 cylinder, I should try it on the 8 cylinder setting to see if that causes it to fail. I would not think so because I think the knob selects resistors.
 
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Dean Huster

Well-Known Member
If you remove the meter movement from the panel and then remove the cover from the meter, you can use a can of dry air to blow any possible contamination from the movement. However, hold the meter pointer against the meter face so that the air doesn't slam it around and begin blowing with the can far away from the movement. You don't want to start with the can right at the movement and then screw the helical springs all up and ruin the meter. As mentioned, because the movement is pretty well enclosed, there really shouldn't be any foreign material in there. But you never know.

I would never consider using any liquid to clean a meter movement.

If you start loosening the adjusting screws, you have to be very, very careful, for you can crack jewels in the movement bearing and ruin the meter when you retighten the screws.

Static build-up can be reduced by wiping down the meter face with a cloth dampened with a water and Downy fabric softener mixture. To see if static is the problem with a stubborn meter, simply open your mouth widely about one inch from the meter face and go "Hahhhhhhhhhh" on it to fog it over or introduce static-killing humidity to the meter face. The indicator needle should hop right to zero if that's where it's supposed to go.

Dean
 
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