Xerox 7700DX - Phaser Color Laser Printer Service Manual page 99

Error Chain /
Code Link
78 09-358
Remove the Waste Cartridge Sensor Holder without disconnecting the harnesses (RRP 23,
on page 7-178).
Measure the voltage between the yellow wire to the Waste Cartridge Full Sensor and frame
ground and alternately interrupt the Waste Cartridge Full Sensor.
Does the voltage toggle between +5 VDC and 0 VDC?
Yes No
Measure the voltage between the gray wire to the Waste Cartridge Full Sensor and
frame ground.
Does the voltage measure +5 VDC?
Yes No
Remove the Rear Cover (RRP 1, on page 7-154) and Rear Shield
(RRP 9, on page 7-163).
Measure the voltage at P406A-3 (see figure page 2-46) on the Engine Control
Board.
Does the voltage measure +5 VDC?
Yes No
Replace the Engine Control Board (RRP 42, on page 7-206).
Inspect the wiring harness between the Engine Board and the Waste Cartridge Full
Sensor. Repair or replace the harness as necessary.
Measure the voltage between the violet wire to the Waste Cartridge Full Sensor and
frame ground.
Does the voltage measure 0 VDC?
Yes No
Inspect the wiring harness between the Engine Board and the Waste Cartridge Full
Sensor. Repair or replace the harness as necessary.
Replace the Waste Cartridge Full Sensor.
Remove the Rear Cover (RRP 1, on page 7-154) and Rear Shield (RRP 9, on page 7-163).
Measure the voltage at P406A-2 (Voltage Measurements on page 2-46) on the Engine Control
Board.
Alternately interrupt the Waste Cartridge Full Sensor again.
Does the voltage toggle between +5 VDC and 0 VDC?
Yes No
Inspect the wiring harness between the Engine Board and the Waste Cartridge Full
Sensor. Repair or replace the harness as necessary.
Replace the Engine Control Board (RRP 42, on page 7-206).
80 04-341
04-343
Switch printer power Off, then On.
If the problem persists, replace the Engine Control Board (RRP 42, on page 7-206).
ERROR 78 WASTE TONER CARTRIDGE FULL DETECTION
SENSOR FAILURE
ERROR 80 ENGINE LOGIC BOARD FAILURE
Phaser 7700 Color Laser Printer Service Manual
Front Panel Message
2-69