Service Manual 4-51Electronics TroubleshootingSystem Power-Up SequenceThe following lists the chain of events that occur when you turn on a printer. You canfollow this list as one means of determining if the printer is operating correctly. Theexact chain of events depends upon the last power down condition and where theprinter has last determined the printhead is positioned, this is stored in non-volatileRAM. The Electronics Troubleshooting Checklist is the primary reference fortroubleshooting 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) andenables DC voltages. If an overload occurs, the printer turns off the high voltageDC 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 nexttest.4. The Boot loader performs CPU initialization and RAM test. It then sends theboot 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. ThePOST version is displayed on the LCD and waits two seconds. During this timethe 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 paneldisplays status messages as each sub-test is performed. This test takes about 8seconds All LEDs are off during the test.If POST diagnostics pass, the front panel displays the Xerox logo and turns onthe green LED.If an error is detected, the error message is displayed on the LCD and the printerflashes the LEDs with a repeating error code pattern.7. The VxWorks operating system is initialized and engine code is started. Thistakes about 15 seconds. The Xerox logo is displayed.8. Print engine self test (PEST) diagnostics are then performed. These test theheaters, clutches, motors and solenoids. As each clutch is tested you will hearclicking and there will be four high tones as each motor is tested. This test takesabout 30 seconds.9. The printer now runs the mechanical initialization. The exact sequence dependson the initial position of the printhead and wiper assembly.
