Bench Testing: Diodes

Connect a 12-volt battery lead, with a 1.5-watt (maximum) test lamp connected in series, to a diode plate. Connect other battery lead, in turn, to each diode pin. See Fig 1. Then reverse the connections.

Fig 1: Testing Diodes in Rectifier Assembly Test lamp should be 1.5 watts maximum.
Lamp should light (with current flow) in one direction only. If lamp lights in both directions or fails in both, replace rectifier pack.