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Diode Trio

  1. Remove diode trio from end frame assembly. Connect one ohmmeter lead to brush connector and other lead to one of 3 stator lead connectors. Then reverse ohmmeter probes. See Fig 1. A good diode will give one high and one low reading. If both readings are same, replace diode trio.
    Fig 1: Bench Testing Typical Diode Trio
    G3505
  2. Repeat test, touching leads in turn from single connector to each of 3 stator lead connectors. If any reading is zero, a short is indicated. Replace diode trio.
NOTE: Before replacing diode trio, check rectifier bridge.