System Boot Sequence; Power On Self Test (Post) - Xerox 7700DX - Phaser Color Laser Printer Service Manual

System Boot Sequence

1. The main power switch is turned On. The health LED turns On
immediately.
2. The boot loader checks for RAM present and functional - if not, 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, Off.
8. The graphic panel turns On, the LED turns Green and the POST tests are
run.

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
Diagnostics Test Descriptions on page 2-34. POST returns control of 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 2-33.
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