3-38 Phaser 7750 Printer Service Manual
Waste Cartridge Full Detection Sensor Failure, Code 78
Troubleshooting References
Applicable Parts Wiring and Plug/Jack Map References
■ Waste Cartridge
■ Waste Cartridge Full Sensor
■ Engine Control Board
Troubleshooting Procedure
Step Actions and Questions Yes No
1
1. Remove the waste cartridge sensor
holder without disconnecting the
harnesses.
2. Measure the voltage between the
yellow wire on the waste cartridge full
sensor and frame ground, alternately
interrupting the sensor.
3. Does the voltage toggle between +5
and 0 VDC?
Go to step 5. Go to step 2.
2
1. Measure the voltage between the gray
wire and frame ground.
2. Does the voltage measure +5 VDC?
Go to step 4. Go to step 3.
3
1. Remove the rear cover and rear shield.
2. Measure the voltage at J407B-17 on
the engine control board.
3. Does the voltage measure +5 VDC?
Inspect the wiring
harness for
damage and
replace, if
necessary.
Replace the
engine control
board.
4
1. Measure the voltage between the
violet wire and frame ground.
2. Does the voltage measure 0 VDC?
Replace the waste
cartridge full
sensor.
Inspect the wiring
harness for
damage and
replace, if
necessary.
5
1. Remove the rear cover and rear shield.
2. Measure the voltage at J407B-16 on
the engine control board.
3. Alternately interrupt the sensor
4. Does the voltage toggle between +5
and 0 VDC?
Replace the
engine control
board.
Inspect the wiring
harness for
damage and
replace, if
necessary.
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