System Boot Sequence; Power On Self Test (Post) - Xerox 7300B - Phaser Color Laser Printer Service Manual

System Boot Sequence

1. When the main power switch is turned on, the health LED on the Image Processor
Board turns on immediately.
2.
The boot loader checks for RAM presence and functionality. If not present or
functioning, it posts a very large "RAM ERROR" on the front panel and blinks the
LED 1/2 second on/off continuously.
3.
The boot loader then runs POST diagnostics.
4. POST turns off the health LED.
5. POST checks the front panel.
6. If keys have been pushed, the front panel displays "Processing Input".
7.
The front panel LED cycles: Green, Yellow, Red, and then off.
8. The front panel turns on, the LED turns Green and the POST tests are finished.

Power On Self Test (POST)

The following tests are performed when the printer is powered on, after the boot
loader runs, and before the operating system is loaded and initialized.
POST diagnostics are intended to provide a quick means of isolating a defective
subsystem associated with the Image Processor Board and SDRAM. POST returns
control to the boot loader and the operating system is loaded. The operating system
then loads the imaging processing software. If POST detected any soft errors, a
message is printed in a red box on the start page. If POST detects any hard errors,
both the front panel and health LED blink the error code pattern, see "LED Blink
Patterns" on page 3-69.
POST Startup indications
At power-on the hardware default is to turn on the IP board 'health' LED.
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The front panel display is reset (addressable area becomes "gray").
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The front panel LED cycles: Green, Yellow, Red, and then off.
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The backlight is turned on (high intensity), with nominal contrast display.
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The front panel display area is turned on, dark black for 1 second.
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The front panel display is cleared.
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The backlight is turned on with nominal intensity.
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The POST Vn.nn message appears, and tests are quickly executed.
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After the POST tests have finished running, the Xerox 'splash screen' is
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posted to the front panel and PostScript begins initialization.
3-68 Phaser 7300 Color Printer Service Manual