Xerox Phaser 7300B, Руководство по обслуживанию

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3-74 Phaser 7300 Color Printer Service Manual
The +5 VDC Loop
Refer to the wiring diagram, "The +5 Volt Loop" on page 10-258 for all procedures
listed under this topic.
Upon power-up the low-voltage power supply (LVPS) generates a +5 volt signal
which is routed out of the LVPS through the engine control board to the toner sensor
board and then back out the toner sensor board to the low-voltage power supply. Once
the +5 volt signal is returned to the LVPS, the LVPS will then turn on all other supply
voltages.
If the low-voltage power supply does not detect the return of +5 volts, the LVPS will
immediately shut-down. You may see the Engine Controller Board LED flash
immediately after power-on.
To verify the +5 volt loop is complete:
1. Test fuse F6 on the Engine Controller Board for continuity. If the fuse is blown
(open circuit), check the circuit for a short to ground.
Note: Disconnect the POWER harness from the Engine
Controller Board prior to checking for a short.
a. If a short to ground is found, systematically disconnect wiring
harnesses on the Engine Controller Board to isolate the short. Replace
the defective wiring harness or component and the Engine Controller
Board.
2.
Verify all wiring harnesses are connected, seated correctly and not damaged.
Replace any damaged wiring harnesses.
3. Check for continuity between the Engine Controller Board OPTN and the
interconnect wiring harness between the toner sensor board and LVPS. If
continuity is not found, the problem is the OPTN wiring, the toner sensor board or
the interconnect wiring harness.
4.
Verify proper operation of the LVPS by bypassing the Engine Controller Board
and the toner sensor board.
a.
Disconnect the power connector from the Engine Controller Board
and disconnect the interconnect between the LVPS and the toner
sensor board.
b. Run a jumper wire between pin 5 on the POWER harness and pin 14
on the wiring harness interconnect, as shown on the +5 Volt Loop
wiring diagram.
c. Turn the printer on. If the jumper connection is correct, the
low-voltage power supply will start and the power supply fans will
run. This indicates the problem lies with the Engine Controller Board
or the toner sensor board or their wiring. If the low-voltage power
supply does not turn on, it is probably bad.
5.
Replace the Low Voltage Power Supply if all other components are operating
correctly.