Xerox 7700DX Service Manual - Page 120
Troubleshooting the +3.3 VDC and +5 VDC LVPS, Troubleshooting the +24 VDC LVPS, harness
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Troubleshooting the +3.3 VDC and +5 VDC LVPS Note Turn the printer power Off and disconnect the power cord. 1. Remove the rear cover and rear shield. 2. Disconnect the harnesses to connectors P501, P574, P801 and 2ndBTR of the T1 HVPS, remove 3 screws and lower the T1 HVPS to horizontal (RRP 44, on page 7-208). 3. Connect AC Power and turn the printer On. 4. Check for proper AC Voltage at the connector at the bottom of the LVPS. If not present go to the Troubleshooting AC Power section (link). 5. Check for +3.3 VDC or +5 VDC at the connector at the top of the LVPS. If correct voltage is not present, unplug the connector and retest. If no voltage is present replace the LVPS. If the voltage returns check the harness, Image Processor Board, Engine Board and Relay Board for shorts. Troubleshooting the +24 VDC LVPS Note Turn the printer power Off and disconnect the power cord. Note The +24 VDC LVPS requires a +5 VDC enable signal to operate. Ensure proper operation of the +5 VDC LVPS before proceeding. 1. Remove the rear cover and +24 VDC PS metal shield. 2. Connect AC Power and turn the printer On. 3. Check for proper AC Voltage at the connector at the bottom of the LVPS. If not present go to the Troubleshooting AC Power section. 4. Check for the +5 VDC enable signal at P505-4 (grey wire). If not check the same signal at the Engine Interface Board P537-6. If not present replace the Engine Control Board (RRP 42, on page 7-206), then the Engine Interface Board (RRP 43, on page 7-207). 5. Check for +24 VDC at any of the orange wires of connector P502 at the top of the LVPS. Unplug the connector and retest. If still no voltage, replace the LVPS (link). If the voltage returns check the +24 VDC circuit for shorts to frame ground in the wiring harness, Engine Board, Relay Board and Interlock Circuit. 3-90 Phaser 7700 Color Laser Printer Service Manual
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