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

Electronics Troubleshooting

Printer 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 Control 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 Control Panel. The Control Panel LED
turns red, green, orange, and then off. The Control Panel LCD then goes black
and then clear. The POST version displays 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 Control
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 Control Panel displays the Xerox logo and turns on
the green LED.
If the test detects an error, the error message displays 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 hear
clicking with 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.
General Troubleshooting 4-59