HP 4550 Service Manual - Page 309

NVRAM initialization NVRAM initialization should always be executed immediately after replacing the firmware or the formatter board. This procedure aligns the firmware with the formatter. Not performing NVRAM initialization could result in deterioration of print quality. Before initializing NVRAM, be sure to gather and write down the information listed below, if possible.
Total page count and color page count. Print a configuration page to obtain both page counts and the serial number.
Percentage of life remaining for both the transfer kit and the fuser kit a. From SERVICE MODE on the printer display panel, press [MENU]. b. Go to SERVICE MENU and press [ITEM]. c. Use the [-VALUE +] keys to go to TRANSFER MAINT COUNT=XXXXXXX and write down the exact numbers shown. d. Go to FUSER MAINT COUNT=XXXXXXX and write down the exact numbers shown.
Serial number. To initialize NVRAM 1 Turn on the printer while holding down both the [CANCEL JOB] and [SELECT] keys until all the LED lights are on, then release the keys. 2 Press [CANCEL JOB]. 3 Press [SELECT]. After replacing the firmware or the formatter board, the following settings are changed or lost. If you do not wish to accept the new values, use Service Mode to enter the previous settings that you wrote down before initializing.
Total page count and total color page count (the counter is reset to 0)
Transfer kit percentage of life remaining (gauge is reset to 100 percent)
Fuser kit percentage of life remaining (gauge is reset to 100 percent)
Printer serial number C7085-90921 Chapter 7 Troubleshooting 307