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TROUBLESHOOTING & REPAIR
STATIC SCR/DIODE RECTIFIER BRIDGE TEST (continued)
FIGURE F.15 – HEAT SINK AND SCR TEST POINTS
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REMOVE INSULATING PAINT
CATHODE
ANODE
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7.Remove the red insulating paint from the heat sink test points. See Figure F.15.
NOTE: Do not disassemble the heat sink.
8.Measure the resistance from the anode to the cathode of SCR 1 using an analog volt/ohmmeter (multimeter) set at R x 1000 scale. See Figure F.15.
a.Reverse the meter leads and measure the resistance from the cathode to the anode of SCR 1. See Figure F.15.
b.If a low resistance is measured in either meter polarity, SCR1 is faulty. Replace SCR 1.
9.Test the resistance of SCR 2 and SCR 3 using the same procedure described in Step 8.
10.Measure the resistance of diode D1 from anode (+probe) to cathode
a.Reverse the meter leads and measure the resistance from cathode (+probe) to anode
b.If a low resistance is measured in both meter polarities, diode D1 is shorted. Replace diode D1.
c.If a high resistance is measured in both meter polarities, diode D1 is open. Replace diode D1.
11.Test diodes D2, D3 and D4 for proper oper- ation using the same procedure described in Step 10.
12.Reconnect all leads and molex plugs. Resolder lead #204 at resistor R3.
13.If this test did not identify the problem or to further test the SCRs, go to the Active
