HP d640 HP D640 High-Volume Printer - User Manual (Printer and Accessories), C - Page 186

Advanced Topics Adjusting Paper Path Alignment Ozone Filter The ozone filter is replaced after every two bottles of developer. If replaced as specified, you should always receive the specified yield. Transfer Unit The transfer unit is replaced whenever the drum is replaced. Care must be taken to prevent accidental breakage of the delicate wires located inside the transfer unit. Unless physically damaged, you will always receive the specified yield. Pushing Consumable Life Beyond Estimated Yields The printer maintains counters to track all consumable use and provides an alert message to inform you when a consumable item needs to be replaced. The printer will not stop, except for lack of toner or developer, but the message remains until you replace the specified consumable. There is a built-in "grace period", so the message to replace a consumable should occur long before you see any print quality or paper jam problems. When you get a "Toner Low" or "Developer end-life" message, it is best to add toner or developer as soon as possible. If toner runs out completely, or the developer reaches its endlife, the printer stops printing to prevent damage to the print engine. Toner and developer are the only consumables for which the printer physically stops. If you have a carefully monitored environment, you can watch the print quality and change the consumables (other than toner and developer) only when absolutely necessary. This tactic may further extend the replacement cycles of your consumables at your own risk. Adjusting Paper Path Alignment Over time, the paper path alignment may change slightly from the factory-set position. The following paper path alignment procedure will set the printing alignment for each tray to ensure correct print position. This procedure looks complicated, but after you have performed it a once or twice, it should only take a few minutes to complete. It may need to be repeated periodically to ensure proper alignment, but if you only print on blank paper, alignment is usually not critical. This procedure sets alignment for both simplex and duplex pages. If you have an HCI installed, you can also set alignment for it. Before proceeding, make sure that there is adequate (20 - 30 sheets) paper in each tray and the HCI (if installed). This amount is necessary for accurate feeding. Note Please read through the entire procedure before performing any of the steps. Advanced Topics 6-11