Rotor Field Winding
Check rotor for grounds or an open circuit with a 110 volt test lamp or ohmmeter (see illustration). Test for grounds between slip ring and rotor shaft; no continuity should exist. Test for an open field by connecting test leads across slip rings, continuity should be obtained. Test for shorts by connecting a 12 volt battery and ammeter in series with both slip rings. Current draw should be 4-4.5 amps. (exc. 80 amp alternators which draw 4-4.9 amps.). Excessive amperage draw indicates shorted windings.