Xerox 4400DT Service Manual - Page 95

Image Processor POST Error Codes The Image Processor Power-On Self-Test (POST) detects two major types of faults: I Hard faults are those that are known to prevent initialization of the operating system used by the Image Processor board CPU. I Soft faults are those that are not a core resource to the operating system, and do not prevent it from initializing and becoming available as a tool for troubleshooting. Soft faults are reported on the Startup Page after the system is running. Fault Reporting Devices There are four fault presentation devices: the health LED, the Front Panel LED, the Front Panel display, and the Start Page. (Refer to Image Processor Board on page 1-10 for the health LED location on the Image Processor Board.) These devices are used only after initial tests indicate they are functioning properly. For hard faults: I The health LED blinks according to the fault code. I The Front Panel LED blinks in unison with the health LED. I The last posted message to the Front Panel display is present. For soft faults: I All soft faults are printed on the Start Page. LED Blink Patterns For faults identified as hard faults, the POST firmware blinks the Health LED in a particular pattern of short and long blinks to identify the fault. A long blink is worth 5 and a short blink is worth 1. If a fault blink pattern is flashed as long, long, short, short, this is fault code 5+5+1+1=12. Note that for test 5, the blink pattern is five short blinks. The exception to the pattern just described is a RAM test error. The RAM tests have a special blink pattern and the front panel displays RAM Error. During power-on the front panel LED is on. If the RAM tests fail, the Image Processor Board health LED turns off, and the front panel LED is red. At 1/2-second intervals, the health LED and the front panel LED toggle continuously. 2-58 Phaser 4400 Laser Printer Service Manual