Xerox 4400DT Service Manual - Page 110
Inoperative Front Panel, Erratic Printer Operation, Inoperative Front Panel Troubleshooting Procedure
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Inoperative Front Panel Front Panel is not operative (no backlight or LED). Inoperative Front Panel Troubleshooting Procedure Step Actions and Questions Yes No 1 1. Disconnect J790 on the Image Processor Board. Go to step 2. Replace the 2. At J790 on the Image Processor Board, measure the Image voltage between frame ground and each pin of J790 listed here. Processor Board Pin Voltage 1 0.0 VDC Pin Voltage 6 3.4 VDC (RRP 9.2 on page 6-88). 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 Are all the voltages are correct? 2 1. Disconnect J550 from the Front Panel. Replace the Replace the 2. Measure continuity on all wires between J550 and J790. Front Panel Front Panel Assembly Harness Are all checks good? (PL 1.1, (PL 1.1, page 7-2). page 7-2). Erratic Printer Operation Erratic Printer Operation Troubleshooting Procedure Step Actions and Questions Yes No 1 1. Disconnect all host cables. Go to step 4. Go to step 2. 2. Enter Service Diagnostics and select Test Print. Run 15 to 20 test prints. Does the printer generate test prints? 2 1. Switch the printer power OFF. Go to step 3. Switch the 2. Disconnect P/J PN1 from the LVPS Assembly. printer power 3. Switch the printer power ON. 4. Check the voltage between P/J281 pin 7 and frame ground. OFF and reconnect PN1. Go to Is the voltage +5.0 VDC? 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 Go to Power Go to step 5. print? Supply on page 3-14. Phaser 4400 Laser Printer Service Manual 3-13
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