Amp meter jumps around

[deburt65]

I have a 1928 Dictator....and was wondered if it is normal for the amp meter to jump from positive readings to a negative reading? The needle doesn't seem to stay still but jumps around a lot, even on the positive reading side. It shows 10-15 amps output, and when dropped into the negative side, is reading less than 5 amps. Do I have a problem or is this normal? The battery seems to be maintaining a good charge. Thanks for any insights.

[Guest stude8]

I have a 1928 Dictator....and was wondered if it is normal for the amp meter to jump from positive readings to a negative reading? The needle doesn't seem to stay still but jumps around a lot, even on the positive reading side. It shows 10-15 amps output, and when dropped into the negative side, is reading less than 5 amps. Do I have a problem or is this normal? The battery seems to be maintaining a good charge. Thanks for any insights.

The ammeter should be steady with the engine at a constant RPM and will read negative at idle but should rise into the charging range when running above 10 MPH normally. If your needle is jumping it might indicate a damaged generator commutator that cause the brushes to not contact the commutator segments continually. A broken brush spring can let a brush jump off the commutator and interrupt the current flow. An incorrect cutout relay or defective one can cause current irregularity to. It could even be a wire in the circuit with missing insulation that allows the circuit to short to ground subject to car vibration when moving. Take a quick observation of the wiring from the generator to the ammeter gauge under the dash for any shabby insulation or loose terminals. If that looks decent then you might have to pull the generator out onto a bench and open it up to examine the internal wiring and brushes for wear or damage. It could even be a brush with the carbon worn away to where it fails to track on the commutator segments. Good luck, you don't want to have a short circuit develope and cause a wiring fire. Stude8