31 ammeter died
 

My ammeter just died.

What tests would you perform to verify that the ammeter is the culprit?

Also, what other tests do you recommend if the ammeter is okay?

Re: 31 ammeter died
 

Use your mulimeter to measure the resistance at the two terminals. If it is infinite then it is toast. The resistance should be very low.

Also test with a your car battery with a light bulb in series with the ammeter. The light bulb will restrict the current so that you do not accidentally blow out the ammeter.

Re: 31 ammeter died
 

Turn the headlights on without the engine running. The ammeter needle should dip into the discharge (negative) side of the face. Pull the instrument panel forward and switch the two wires on the back of the ammeter around. Turn the lights back on. The ammeter needle should go into the charge (positive) side of the face. If the needle responds as described in both tests, the ammeter is o.k. The problem lies elsewhere, such as in the wiring inside the terminal box or a burned-out generator/defective cutout.
Marshall

Re: 31 ammeter died
 

By the way, while the instrument panel is pulled forward, wiggle the ammeter terminal posts to check for looseness. If there is movement, tighten the lock small lock nut between the ammeter and the wire end. If there is still movement, the ammeter is probably broken inside. Also check for signs of burn splotches on the back of the ammeter, indicating a loose wire or loose terminal post.
Marshall

Re: 31 ammeter died
 

Here is a temporary roadside fix for a failed ammeter.

Re: 31 ammeter died
 

Replacement ammeters vary in their quality.

The common replacement is 30-0-30 which are not original in markings but seem popular in production because of the 12V conversion crowd.

Finding a 20-0-20 is only slightly more difficult and one can resort to an Ebay "original" - although the bezel is usually tarnished as a result of nearly 100 years in the environment. The bezel ring can be removed and re-plated with one of the "foam brush" replaters commonly used for small area nickel. (www.caswellplating.com)

Repops can be found in 20-0-20, usually seen with an aluminum bezel ring.

One downside I've seen with the repop is they can be slightly "undersized" and bending the tabs out won't hold them in the panel hole. A solution to this I've found in backing up the meter in the hole with a 1-1/2" rubber o-ring such that the tabs bear on the thin o-ring rather than the panel back - it's a way to compensate for something which SHOULD have been made better.

Joe K

Re: 31 ammeter died
 

make sure the back posts arent touching the tank............

Re: 31 ammeter died
 

If you can't find an o-ring and get a reproduction and it is loose ,put a little RTV silicone dot on the back side of it after it is mounted (less messy)in the opening and spread it to the rear of the dash panel . Make sure it is straight.Let it cure before mounting dash panel in place.

Re: 31 ammeter died
 

Follow up:

All the tests that were mentioned to do on the above posts on the ammeter proved that it was ok. It was a bad wire to the cutout.

Re: 31 ammeter died
 

Ahhh, The old bad wire thing. It is always a bad wire or bad connection somewhere.

Glad you got it fixed.