HP Color LaserJet 8500 Service Manual - Page 432

Note Service mode formatter diagnostics 1 From the Service Mode Menu, press MENU until FORMATTER DIAGNOSTICS appears. 2 Press SELECT. WARNING MEMORY LOSS appears on the printer control panel briefly. Then EXECUTE TESTS appears. 3 Press ITEM until one of the following tests appears on the printer control panel: • ROM CRC - The read-only memory cyclic redundancy check reads the values stored in the firmware ROMs, computes checksum variables based on the read information, and compares the computed checksums with those stored in the ROM. • DRAM DIMMS - Installed DIMMs are tested to ensure that they are supported by the formatter board and are functioning properly. The time that this test takes to run varies depending on the amount of memory installed. DRAM DIMMs are tested using a pattern test, an address test, and a walking ones test. • IDE ASIC - This test is performed on the IDE ASIC of the formatter board to ensure read and write integrity. Values are written to the ASIC registers and then read for verification. • DISK - The disk drive test does the following: a instructs the disk drive (if installed) to perform its internal self-test (similar to a power-on test) b enters into sleep mode and wakes up again c seeks and reads sequential sectors forward for 30 seconds d seeks and reads sequential sectors backward for 30 seconds e seeks and reads random sectors for 30 seconds f performs read and write tests • VX ASIC - This test is performed on the VX ASIC of the formatter board to ensure read and write integrity. Values are written to the ASIC registers and then read for verification. 4 Press - VALUE + until ON or OFF appears on the display. 5 Press SELECT. 6 Press ITEM until EXECUTE TEST appears on the printer control panel display. 7 Press SELECT. Turn the printer off and on to exit the formatter diagnostics. 430 Chapter 7 - Troubleshooting EN