Electronics Troubleshooting; System Power-Up Sequence - Xerox Phaser 8400 Service Manual

Electronics Troubleshooting

System Power-Up Sequence

The following lists the chain of events that occur when you turn on a printer. You can
follow this list as one means of determining if the printer is operating correctly. The
exact chain of events depends upon the last power down condition and where the
printer has last determined the printhead is positioned, this is stored in non-volatile
RAM. The Electronics Troubleshooting Checklist is the primary reference for
troubleshooting power-up problems.
1.
Power cord is plugged in and the power switch is turned on:
2. Power supply senses AC line voltage conditions (110 VAC or 220 VAC) and
enables DC voltages. If an overload occurs, the printer turns off the high voltage
DC supplies causing a "blink" effect on the front panel LEDs.
3. BIST test flashes the PE LED very briefly at a fast rate until the end of the next
test.
4.
The Boot loader performs CPU initialization and RAM test. It then sends the
boot loader version to the serial port.
5.
Power-on self-test (POST) initializes the front panel; front panel LED turns red,
green, orange, and then off, the front panel LCD goes black and then clear. The
POST version is displayed on the LCD and waits two seconds. During this time
the operator can press the Back button to bypass the remaining POST test.
6.
Low level power-on self-test (POST) diagnostics are performed. The front panel
displays status messages as each sub-test is performed. This test takes about 8
seconds All LEDs are off during the test.
If POST diagnostics pass, the front panel displays the Xerox logo and turns on
the green LED.
If an error is detected, the error message is displayed on the LCD and the printer
flashes the LEDs with a repeating error code pattern.
7. The VxWorks operating system is initialized and engine code is started. This
takes about 15 seconds. The Xerox logo is displayed.
8.
Print engine self test (PEST) diagnostics are then performed. These test the
heaters, clutches, motors and solenoids. As each clutch is tested you will hear
clicking and there will be four high tones as each motor is tested. This test takes
about 30 seconds.
9.
The printer now runs the mechanical initialization. The exact sequence depends
on the initial position of the printhead and wiper assembly.
Service Manual 4-51