Power Supply - Xerox Phaser 8400 Service Manual

the configuration card, and does not change. Ethernet address is stored only on the
configuration card, and cannot be rewritten. The ethernet address is not written to the
NVRAM chip.
Personality parameters are a subset of network configuration parameters which are
populated to the configuration card over time, as the printer is configured by the
customer. The personality parameters are copied, or "shadowed", from the main
board's NVRAM chip to the configuration card during the normal operation of the
printer. When the configuration card is inserted into a new printer, the personality
parameters on the configuration card are written into the NVRAM chip of the new
printer. When a printer is powered on, if it contains the configuration card of another
printer, the personality parameters are automatically copied to the NVRAM chip. If
the configuration card is removed, the printer will reboot as a B (non-networking)
model configuration. Refer to the "Configuration Card Personality Parameters"
section at the end of this chapter for a detailed list of "shadowed" personality
parameters.
Power Control Board
The power control board distributes drive voltages to operate the printer's various
motors, solenoids and clutches. The power control board also provides the interface
that returns information from the printer's sensors to the main board. The sensors are
used to track mechanical and thermal functions, such as the position and temperature
of the printhead. The power control board also generates regulated +/- 12 volt (V) and
5 V from unregulated +/-15 V power.

Power Supply

There are no field adjustments necessary on the power supply. In general, the power
supply has two main, yet interrelated sections: the AC section and the DC section. In
the AC section, power is routed to 10 triacs which, under main board logic control,
supply AC power to the 10 heaters in the printer.
Two fuses provide current protection to the triacs. Fuse F2 and F3 protect the power
supply from, most often, a shorted triac caused by a defective heater. If the F2 or F3
fuses blow, it is best to replace the electronics module (and, of course, the defective
heater), rather than the fuse. Otherwise uncontrolled, with the fuse replaced but the
triac shorted, AC power may be applied to the heater. Each time the main board turns
on a triac to activate a heater, it is turned on for only a fraction of a second. The main
board must constantly readdress each heater it wants to remain on. This means if the
print engine firmware should fail, the heaters automatically shut off.
The printer is also protected by thermal fuses. A thermal fuse opens in the unlikely
event of a "runaway" heater following a hardware failure. The drum and the paper
preheater thermal fuses are located on the paper preheater. Additional thermal fuses
are located on the printhead and on the ink melting elements.
Service Manual 2-5