1. Connect ohmmeter a cross terminals L1 and T1. Resistan ce reading should be greater than
50,000 ohms.
2. If reading is less than 50, 000 ohms, remove connect ing bus heatsink betw een SCR3 and
SCR6 and check anode to c at hode of SCR3 and SCR6 separa tely to determine whi c h
device is defective. See Figure 46. Replace defective devic e and retest con troller.
3. Repeat Steps 1 and 2 across t erminals L2 and T2 for SCRs 2 and 5.
4. Repeat Steps 1 and 2 across t erminals L3 and T3 for SCRs 1 and 4.
If the SCRs tested were no t defective but the prob lem s t ill persists, refer to t he f ollowing
Steps 5 and 6.
5. Disconnect the SCR1 f r om th e white gate and red cathod e wires on the AK control lo gic
card. With an ohmmeter set on Rx1, check between white and red wires. Resist ance should
normally be between 8 and 20 ohms average. Excessively high or low resistance may be
indicative of a defect ive device. Replace and r et est.
6. Repeat Step 5 for SCR l eads 2 through 6. Ca re should be taken to ens ure that the gate and
cathode wires are rep lac e d exactly as they were: white wire to gate (G1 thro ugh G6); red
wire to cathode (K1 through K6).
IMPORTANT: Before performing the SCR chec k below, remove power from the starter
and disconnect the motor terminals T1, T2, and T3.