tom102

I just picked up a used ammeter to replace the dead one in my 76 vette. Before I tear the dash and bezel apert to install it I would like to make sure it works ok. We just put an ohmeter across the two terminals on the back of the ammeter and show continuity between the two terminals can I safely assume the meter is good? Or is there another way of testing it out?


[Modified by tom102, 7:00 PM 2/14/2004]

vettemack

DO NOT PUT AN OHMMETER ACROSS THE TERMINALS!!! It will peg the meter and damage it.
The meter movement is usually a very low current, 50microamps/500microamps, or so. That is 50/1,000,000 amps.
You would need the shunt off your old meter to test correctly or a current output of 0-50 ua. This would be hard to find unless you were involved in test equipment calibration or have a friend in that business.

ettev

:eek:
The guy that rebuilt mine at Corvettes at Carlisle checked all his with an ohm meter. I can't imagine a check like that for anly a fraction of a second would hurt the meter.

tom102

When I recieved the ammeter the fellow that had it put an ammeter across the terminals to show me it was working and it did show continuity however the needle on the gauge did not move at all when he did that. I thought that was ok as no electric was being applied to it. Was I wrong in assuming this?


[Modified by tom102, 7:01 PM 2/14/2004]

JOliver

You're correct
You can use an ohmmeter on it without any problems...You can even take a power supply or a battery and tap it just for a second to see if it jumps.
I have the proper equipment to do this with but a small power supply with a breaker is ideal....And there is No shunt resistor on a battery gauge.

VetteInstruments@aol.com
Jason

tom102

Can I use my 12v battery charger to test the meter function by hooking the positive side to one of the terminals and the neg lead grounded on the case of the meter? or is this a fast way to burn up the gauge. Like I said there is continuity across the terminals. I am not that good with electrical stuff and tend to burn things out thats why I am asking

Mike Ward

Even easier and safer is using a 1.5 volt flashlight battery. Just touch the contacts for a brief millisecond to see if the gauge needle moves.

turtlevette

YES, Thats what i would recommend. Shorting across a car battery or charger is not a good idea, you are going to get a 400 amp punch out of a car battery which can damage the meter. You may damage your battery charger by shorting it through the ammeter.

An ohm meter to show continuity is a good test too. The guy who thinks you are going to damage the ohm meter is wrong.




[Modified by turtlevette, 2:16 PM 2/15/2004]

KenSny

I agree: Use a small AAA battery and QUICKLY touch the gauge terminals and the needle should swing one way, then reverse the leads and the needle should swing the other way. This will NOT destroy a working meter.

tom102

Thank all of you for your help :) I tested the gauge using a AAA battery with a momentary contact on the terminals of the gauge and the needle moved in one direction then reversed the contact points and the needle moved the other way. Now I can take the dash gauge bezel out of the car to install what I know is a working gauge. Thanks again for the help.


[Modified by tom102, 7:49 PM 2/15/2004]