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Phaser 8400/8500/8550/8560 Color Printer Service Manual 4-51
General Troubleshooting
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.