Xerox Phaser 8400 Service Manual page 207

d.
Plug in the Power Control to I/O board connector (J800). This step adds the
I/O board back to the working electronics module - nothing else is
connected.
e. Turn on power to the printer
5. If the PE and PS indicators do not flash momentarily, the short is on the I/O board
or related cabling. Skip the rest of this section if the PE and PS indicators flash
because the problem is elsewhere in the printer.
a.
Verify short is on the I/O board by using an ohmmeter to check the resistance
on J270, pin 1 to ground. Resistance of less than 1K ohm indicates a
problem.
b.
To isolate problem to I/O board or related cabling, unplug I/O board
connectors:
■
Umbilical Right J1
■
Waste Tray Sense J110
■
Stripper Solenoid J250
■
Paper Tray Sense J610
■
Front Door Sense J600
■
Inkload Signal J910
■
DMU Sense J860
■
Drum Thermistor J870
■
Exit Module J680
■
Heater Relay Control J950
c.
Retest the resistance of the I/O board. If the resistance is still less than
1K ohm, replace the I/O board, reinstall all cables and retest printer.
d. If the I/O board resistance is OK, plug in the I/O board connectors one at a
time and retest the resistance.
e. Plug in all cables removed during service.
f.
Trace through all service steps performed to reattach any cables that were
unplugged during debugging.
g. Attach printer covers.
h.
Perform full test of printer.
6. Short circuit on 3.3 V power supply within the Control Panel.
a. REQUIRED: Follow all procedures from Step 3 and Step 4 before
proceeding.
b.
With power cord connected, touch the metal electronics module to discharge
any static electricity.
c. Turn off printer and wait 30 seconds for power supply capacitors to
discharge. Damage to circuits within the electronics module may occur if the
power supply capacitors are not allowed to fully discharge.
d.
Plug in the Control Panel connector J220 on the I/O board. This step adds the
Control Panel back to a working electronics module and I/O board in order
to see if the short circuit is also removed.
e.
Turn on power to the printer.
General Troubleshooting 4-67