Power Supply - Xerox Phaser 8400 Service Manual

transfer the printer configuration. Feature value and ethernet address are configured at
the factory, and are "read only". The feature value is fixed in 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 when the customer configures the printer. The
personality parameters are copied ("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 copy automatically to the NVRAM chip. When removing the
configuration card for the Phaser 8400, the printer reboots as a B (non-networking)
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
track mechanical and thermal functions, such as the position and temperature of the
printhead. The power control board also generates regulated +/- 12 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 sections: the AC section and the DC section. In the AC section,
power routes to 10 triacs. Under main board logic control, the triacs 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 a shorted triac from 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. With the fuse replaced but the triac shorted, AC power may be applied
to the heater. However, 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 re-
address each heater it wants to control. If the print engine firmware should fail, the
heaters would automatically shut off.
Thermal fuses also protect the printer. 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.
2-20 Phaser 8400/8500/8550 Color Printer