Xerox 6250N Service Manual - Page 167

POST Faults There are two kinds of faults: soft and hard. A soft fault is any fault that is discovered by POST, but does not prevent the operating system from initializing and becoming available as a tool for troubleshooting. These POST faults do not stop execution and are reported on the StartPage in a red box after the system is running. A hard fault is any fault discovered by POST that prevents the operating system from initializing successfully. A hard fault prevents the system from further execution and is halted with blinking LEDs (front panel and health LED). The test name of the test that failed is displayed on the front panel. Fault Reporting Devices There are four fault presentation devices. ■ All soft faults are printed on the StartPage. For hard faults: ■ The health LED flashes according to the fault code. ■ The front panel LED flashes in unison with the health LED. ■ The last posted message to the graphic front panel is present. LED Blink Patterns For faults identified as hard faults, the POST firmware causes the IP health LED to blink in a particular pattern to identify the fault. There are short and long blinks. 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, which indicates a failure in the CPU interupt test. See "POST Diagnostics Test Descriptions" on page 4-7. The exception to the above pattern is a RAM test error. The RAM tests have a special blink pattern and the front panel displays "RAM Error". During power up the front panel LED is on. If the RAM tests fail, the Image Processor Board health LED is turned off, and the front panel LED is red. At 1/2-second intervals, the health LED and the front panel LED toggle continuously. 4-6 Phaser 6250 Color Laser Printer Service Manual