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Ammeter

G

GordoSD

Well-known Member
Is there a bench test I can do at home for the ammeters found on the H, M, SM's? I have several I want to test before I install on running tractors that have suspect ammeters.
BTW big thanks to Bob M, I used his digrams to completely rewire my two restorations underway. (H, SMTA)

Gordo
 

Battery + ----- headlight bulb ------ ammeter ----- battery -

6V or 12V doesn't matter. Amps are Amps and the ammeter doesn't care. If the needle moves, and the light goes on, it's working.
 
Gordo - This quick test also works:

1 - Bring a small magnet near the face of the meter - the pointer should deflect left and right of 0 as you move the magnet around. If the pointer does not move the pointer is stuck - toss the ammeter in the trash.

2 - Check for continuity between the two ammeter posts - a working ammeter will show 0 ohms.

----

Glad to hear my diagrams helped your rewiring job! ...Bob M
 
You can just use some jumper wires,,,,,,,,,the ammeter in question,,,,,,,,,,a battery,,,,,,,a load such as a head or tail light etc. to run a "bench test" as you asked...

The SERIES circuit could run typically from the battery Pos post,,,,,,,to and through the ammeter in series,,,,,,,,to and through a headlight etc.,,,,,,,,,return to the batterys other Neg post. The needle should deflect typically say 3 to 5 or more amps (depends on load ohms) and then if you reverse the ammeter leads it should deflect thE opposite direction....

With just an ammeter and an ohm meter,it should read very low ohms continuity through the ammeter but if its open its baddddddddd. It can still be continuous, however, but still a bad ammeter mechanically speaking due to a rusted/stuck/corroded needle assembly

John T
 
They passed the magnet and the ohmmeter tests. Now to make some more alligator test leads, or grow four more hands>
Thanks guys

Gordo
 
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