Xerox 4400DT - Phaser B/W Laser Printer, Service Manual, Page: 110 / 503

Phaser 4400 Laser Printer Service Manual 3-13
Inoperative Front Panel
Front Panel is not operative (no backlight or LED).
Erratic Printer Operation
Inoperative Front Panel Troubleshooting Procedure
Step Actions and Questions Yes No
1 1. Disconnect J790 on the Image Processor Board.
2. At J790 on the Image Processor Board, measure the
voltage between frame ground and each pin of J790
listed here.
Are all the voltages are correct?
Go to step 2. Replace the
Image
Processor
Board
(RRP 9.2 on
page 6-88 ).
2 1. Disconnect J550 from the Front Panel.
2. Measure continuity on all wires between J550 and
J790.
Are all checks good?
Replace the
Front Panel
Assembly
(PL 1.1,
page 7-2 ).
Replace the
Front Panel
Harness
(PL 1.1,
page 7-2 ).
Erratic Printer Operation Troubleshooting Procedure
Step Actions and Questions Yes No
1 1. Disconnect all host cables.
2. Enter Service Diagnostics and select Test Print. Run
15 to 20 test prints.
Does the printer generate test prints?
Go to step 4. Go to step 2.
2 1. Switch the printer power OFF.
2. Disconnect P/J PN1 from the LVPS Assembly.
3. Switch the printer power ON.
4. Check the voltage between P/J281 pin 7 and frame
ground.
Is the v5.0 VDC?
Go to step 3. Switch the
printer power
OFF and
reconnect
PN1. Go to
Power
Supply
on
page 3-14.
3 Replace the Engine Logic Board (RRP 9.3 on
page 6-89 ).
Does the problem still appear?
Go to
Electrical
Noise
on
page 3-33.
Problem
solved.
4 Does the printer RESET while generating test
print?
Go to Power
Supply on
page 3-14.
Go to step 5.
Pin Voltage Pin Voltage
1 0.0 VDC 6 3.4 VDC
2 3.4 VDC 7 0.0 VDC
3 0.0 VDC 8 0.0 VDC
4 3.4 VDC 9 5.0 VDC
5 0.0 VDC 10 5.0 VDC