Thumping Noise When Printing, Caused By Flat Spots on Fuser Assembly

The fuser assembly may stay in one position long enough to cause a flat spot on one of the fuser rollers. If this flat spot has occurred, the HP LaserJet 9000 series printer may make a thumping noise when printing or during a rotation of the fuser rollers. The noise (thumping) will not affect the performance of the printer. It is only a noise issue.

There has been a timing change to the DC Controller to eliminate the fuser rollers staying in the same position too long.

NOTE: There is a Modification Recommended Service Note for this issue that involves replacement of the Fuser and DC Controller.

NOTE: Verify the DC Controller version (printer number on configuration page), if it is already 1C then it does not have to be replaced.

Instructions on replacing the DC Controller

Turn the printer off and unplug it.

Remove two silver screws (Figure 1, call-out 1) from the right back cover.

Remove seven gold screws (Figure 1, call-out 2) from the back cover.

Remove the back cover and right back cover as one part, see Figure 1.

 Figure 1: Back Cover 1-Two Silver Screws 2-Seven Gold Screws

CAUTION: The flat ribbon cable is fragile. Do not bend or fold it.

Remove the flat ribbon cable connector (Figure 2, call-out 1) from the DC Controller

Unplug the low-voltage power supply cable connector (call-out 2) from the DC controller, and unroute the cable from the cable guides (Figure 2, call-out 3).

Figure 2: Remove connectors 1-Flat ribbon cable connector 2-Low-voltage power supply cable 3-Cable guides

Remove three silver screws (Figure 3, call-out 4)

Push the black locking tab (Figure 3, call-out 5) away from the HVPS, and remove the HVPS.

Figure 3: Remove screws1- Three silver screws 2-The black locking tab that holds in the HVPS

CAUTION: Be very careful when removing cable connectors J-215, J-219 and J-213. DO not bend or break the component that is adjacent to these cable connectors.

Remove the 17 cable connectors (Figure 4, callout 1).

Figure 4: Remove connectors 1-17 Cable connectors

Remove the four gold screws (Figure 5, callout 2).

Release the small tab (Figure 5, callout 3), and rotate the top edge of the DC Controller away from the printer.

Remove the DC Controller from the two metal holders (Figure 5, callout 4).

Reinstall in the reverse order, be careful when reconnecting the cable connectors to the DC Controller.

Figure 5: Removing the DC Controller 1-Four Gold Screws 2 -Small Tab 3-Two Metal Holders

Service Menu Stand-by Fuser Mode Settings for Fuser Flat Spots

Changes have been made to the DC controller firmware to alleviate the occurrence of flat spots by changing the stand-by fuser temperature and frequency that the fusing rollers turn. Though this new DC controller version (1C) has effectively resolved this issue for many customers, some customer print/copy use models can still contribute to the development of flat spots on the fusers. Customers that mainly print short jobs, print/copy infrequently or turn off the product may have a flat spot develop on the fuser in their printer.

In order to alleviate the occurrence of flat spots for customer that still experience the issue, a change in the print engine firmware has been developed to allow the stand-by temperature of the fuser pressure roller to be adjusted.

NOTE: This new menu option is only accessible through the Service Menu and not accessible by the end user/customer.

NOTE: The printer/MFP needs to have firmware upgraded to the latest version on the web in order for this menu to be visible in the Service Menu.

Options available in this selection are as shown in Figure 2:

Figure 7: Options within Stand-By-Fuser Mode Menu

There are four fuser stand-by temperatures that may be selected in this menu:
140 C
125 C
110 C (recommended setting)
OFF
These temperature selections are available only in DC controller version IC. The default temperature of DC controller 1C is 125 C. When the printer enters stand-by mode, the fuser pressure roller cools from READY temperature to 125 C.

NOTE: The recommendation is to set the Fuser Stand By Mode to 110 C.If the issue still occurs after making this change then the setting needs to set to OFF and the customer informed that it will take longer for the fuser to warm up to printing temperature from Stand By Mode.

© 2005 Hewlett-Packard