TUBE AS 4562934 - Caterpillar

Rectifier Diode Test
The following procedure tests each of the six diodes within the rectifier diode module. If any meter reading does not fall within the given ranges, replace the heat sink assembly. Refer to the "Removal/Installation" instructions.
High voltage may be present. The power source must be disconnected before working on the equipment. Failure to disconnect the power source could result in injury or death. Verify that the equipment is not energized before performing any maintenance. This work must be performed by trained personnel with correct tools and procedures. Bodily contact with electrical potential will cause personal injury or death.
Remove all leads from the rectifier diode module.
Set the digital multimeter to the diode range.
Place the black test lead of the multimeter on the positive "+" rectifier diode module terminal.
Place the red test lead of the multimeter on each of the following rectifier diode module terminals. Begin with "AC1", then "AC2", and finally "AC3".Note: All the meter readings must be between 0.4 VDC and 1.0 VDC.
Place the red test lead on the negative "-" rectifier diode module terminal.
Place the black test lead of the multimeter on each of the following rectifier diode module terminals. Begin with "AC1", then "AC2", and finally "AC3". Note: All the meter readings should be between 0.4 VDC and 1.0 VDC.
Place the red test lead of the multimeter on the positive "+" rectifier diode module terminal.
Place the black test lead of the multimeter on each of the following rectifier diode module terminals. Begin with "AC1", then "AC2", and finally "AC3". Note: In all cases, the meter should read "OL"(overload).
Place the black test lead of the multimeter on the negative "-" rectifier diode module terminal.
Place the red test lead of the multimeter on each of the following rectifier diode module terminals. Begin with "AC1", then "AC2", and finally "AC3". Note: In all cases, the meter should read "OL" (overload).Note: A shorted diode can damage