Xerox Phaser 8400 Service Manual page 208

f.
If the PE and PS indicators do not flash momentarily, the short is on the
Control Panel. Replace the Control Panel and retest the printer. Skip the rest
of this section if the PE and PS indicators flash because the problem is
elsewhere in the printer.
g. Plug in all cables removed during service.
h.
Trace through all service steps performed to re-attach any cables that were
unplugged during debugging.
i.
Attach printer covers.
j.
Perform full test of printer.
7.
Short circuit on 3.3 V power supply within the printhead.
a. REQURIED: Follow all procedures from 'Short circuit on 3.3 V power
supply within the electronics module' before proceeding. The following
procedure relies on a working electronics module to determine if the
printhead is causing a short circuit.
b. With power cord connected, touch the metal electronics module to discharge
any static electricity. ESD damage to the printer may occur if static
electricity is discharged to printer electronics.
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 printhead interface connector (J130) to the electronics module.
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.
f.
If the PE and PS indicators do not flash momentarily, the short is on the
printhead. Replace the printhead and retest the printer. Skip the rest of this
section if the PE and PS indicators flash because the problem is elsewhere in
the printer.
g. Carefully test the printer to ensure damage to the electronics module did not
occur due to the shorted printhead.
h.
Plug in all cables removed during service.
i. Trace through all service steps performed to reattach any cables that were
unplugged during debugging.
j. Attach printer covers.
k.
Perform full test of printer.
4-68 Phaser 8400/8500/8550 Color Printer