Xerox Phaser 7400 Service Manual page 276

Troubleshooting Procedure Table
Step Actions and Questions
1 Test the Drum Phase Sensor for the
affected color.
Run the Service Diagnostics Drum Phase
Sensor test.
Does the sensor function correctly?
2 Test the affected Imaging Unit Motor.
1. Close the Interlock Switches for test.
2. Run the appropriate Service Diagnostics
motor test.
Does the motor operate?
3
Check for +24 V to the motor.
Is there +24 V across DC(0,1,2,3)- 3 <=>
ground?
4 Check Motor Driver Board POW24
connector for 24 V.
1. Disconnect POW24.
Is there +24 V across POW24-1 and 2?
5 Check for 24 V at the LVPS
1. Disconnect CN2 on the LVPS.
Is there +24 V across pins 1 and 2?
6 Check all pins of the DRV1 harness for
continuity.
Disconnect the DRV1 ribbon cable.
Is the cable conductive?
7 Check the Imaging Unit Sensor Board
connection.
Is the CTG0 Harness connected?
8 Check all pins of the CTG0 harness for
continuity
Disconnect the CTG0 Harness.
Is the harness conductive?
3-166
Yes
Go to Step 2.
Replace the
affected Imaging
Unit. If the error
persists, go to
Step 3.
Go to Step 6.
Replace the Motor
Driver Board
(page 8-141).
Replace the
POW24 Harness.
Go to Step 7.
Go to Step 8.
Replace the Engine
Control Board
(page 8-112).
Phaser 7400 Color Printer Service Manual
No
Replace the
Imaging Unit
Sensor Board
(page 8-142). If the
error persists, go
to Step 2.
Replace the motor
(page 8-106). If the
error persists, go
to Step 3.
Go to Step 4.
Go to Step 5.
Replace the LVPS
(page 8-121).
Replace the DRV1
Harness.
Connect the
Imaging Unit
Sensor Board.
Replace the CTG0
harness.