Control Panel Displays Black Boxes (or Squares), Asterisks, or Is Blank

The HP LaserJet 9000/9050 series printerdoes power up (can be verified by listening for fans); however, the Control Panel display is unreadable. It contains asterisks or is blank. Frequently, an improperly seated formatter, memory or firmware DIMM in the wrong slot causes this issue. Incompatible third-party memory can also cause this issue. Refer to the following for troubleshooting steps to isolate and resolve the issue.

NOTE: It is critical to first verify if the printer is actually powering up by listening for fan activity. If the printer does not have fan activity, then the issue is related to a power failure.

Verify at power on that the machines fans are present, easiest fans to verify with either by feel or listening are the output delivery fans. If the fans are on or rotating, then continue to the next step; if they are not rotating, then the issue may be related to power. Please troubleshoot the issue as a power failure.

An engine test should be performed without the formatter installed in the printer. The engine test verifies that the print engine is functioning correctly. This test is very useful for isolating printer problems. A successful engine test indicates that the motors, laser scanner, drive assemblies, and sensors are working correctly. The engine test prints a full page of horizontal lines across the entire printable area. If the formatter is installed, the engine test can be printed from either Tray 2 or 3. With the formatter removed, the tray not being printed from must be opened to force the printer to pull from the proper tray. The print cartridge must also be installed in the printer. To perform an engine test, do the following:

Turn the printer off and remove the formatter. The Engine Test button is located on the DC controller. It is accessible through a small hole at the right rear of the printer as shown in Figure 1, call-out 1. To print an Engine Test page, use a pencil or bent paper clip to push the switch in.

NOTE: Without the formatter installed the control panel will be blank with no illumination upon power up.

Press the engine test button while powering on the printer. Keep the Engine Test button pressed in for 10 to 15 seconds while powering on the printer, and then release the engine test button.

Wait three full minutes, and then press the Engine Test button again. An Engine Test page will now print out. If you keep holding the Engine Test button down the printer will continue to print Engine Test pages until the Engine Test button is released. Figure 2 shows what a successfully printed Engine Test page looks like.

To return the printer back to a normal state power off the printer, reinstall the formatter, and power the printer back up.
NOTE: Three minutes is the amount of time it takes for the fuser to warm up from a cold state. The engine test will fail to print if the fuser is not ready (adequately warmed up) and will give the impression that there is a problem when in reality there is not. If the printer has been running just prior to performing the engine test (not in POWERSAVE), it will only be necessary to wait 15 to 30 seconds after performing Step b. To play it safe and avoid a false result, wait the full three minutes. The engine test can be immediately printed again by pressing the Engine Test button, as long as the printer has not been powercycled after performing Steps b and c.

Figure 1: Right rear of printer 1 - Location of Engine Test switch

Figure 2: Example of Engine Test page

Engine test was successful

If the engine test was successful, then the issue is most likely with the formatter or memory/firmware DIMMS. In most cases, just reseating the DIMMS, verifying they are in the correct slot and properly reinstalling the formatter will resolve the issue. Incompatible third-party memory may also cause this issue. It is very important to verify the memory DIMM configuration on the formatter according to the following tables below which lists the maximum amount of memory allowed for each DIMM slot as well as the proper DIMM configuration for HP LaserJet 9000 series printers.

NOTE: When installing the formatter make sure it seats properly and that the thumbscrews are hand tight. An improperly seated formatter can cause this or other issues.

Engine test was not successful

If the engine test does not work continue troubleshooting the issues using the following steps. There are a number of errors that can cause the engine test to fail. With a non-functional control panel it is impossible to tell what these errors are. An error as simple as Install Toner Cartridge (caused by an improperly installed print cartridge or the absence of one) can prevent an engine test from being performed.

HP LaserJet 9000 DIMM configuration

For HP LaserJet 9000 series printer models, the firmware DIMM must be in Slot J1 and the 64 MB memory DIMM can be installed in any of the other slots. For testing purposes, all other DIMMS should be removed, along with the hard disk and HP Jetdirect cards (if equipped). Rebuild the original configuration by adding each of these back onto the formatter one at a time, retesting with each addition.

Slot label on the Configuration page

Slot label on the formatter board

Slot 1

J1

Flash firmware (mandatory)

Slot 2

J2

64 or 128 MB (Printer models)

Slot 3

J3

64 or 128 MB

Slot 4

J4

64 or 128 MB

CAUTION:If no memory is present on the formatter the printer will boot up to a 53.10.03 error.

If the printer returns to a READY status in a minimal configuration (Firmware DIMM in Slot J1, the minimum required memory installed in another slot and no HP Jetdirect cards installed), then try testing with the remaining memory DIMMS one at a time. Examine the DIMM slots on the formatter as well as the connector on the formatter that plugs into the DC controller for damage at the same time. If there is any damage to the formatter, then replace it.

If after performing the previous testing the engine test is successful but the display is still blank or shows asterisks, then replace the firmware DIMM. If the printers control panel comes back to a READY status, ensure firmware is upgraded. If the printers control panel is still unreadable, replace the formatter.

The least likely cause of this issue is a defective control panel. If all the previous testing has been performed and formatter/firmware has been replaced and the display is still blank or shows asterisks, then remove the control panel and reseat the control panel cable connector J206. If this still does not fix the issue, then replace the control panel.

If all the previous troubleshooting still does not resolve the issue, then replace the DC controller.

NOTE: Technicians: If the issue still has not been resolved at this point call Hewlett-Packard for further assistance.

Replacing the control panel

Open the front cover.

Release the two tabs (shown in Figure 3, call-out 1) on the underside of the control panel by pulling them toward the front of the printer.

Unplug the cable connector on the underside of the control panel, and remove the control panel from the printer.

Reinstall in the reverse order.

Figure 3: Control panel1 - Pressing here will remove the control panel.

Instructions on replacing the DC controller

The formatter needs to be removed first, followed by the back cover, then the high-voltage power supply (HVPS) to access the DC controller.

Removal and replacement instructions for the back cover

Turn the printer off and disconnect the power cable.
Remove two silver screws (Call-out 1) from the right back cover.
Remove seven gold screws (Call-out 2) from the back cover.

Figure 4: Back cover1 - Two silver screws 2 - Seven gold screws

Remove the back cover and right back cover as one part.

Removal and replacement instructions for the high-voltage power supply (HVPS)

Remove the back cover.

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

Remove the flat ribbon cable connector (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 (Call-out 3).

Figure 5: Remove connectors 1-Flat ribbon cable connector 2-Low-voltage power supply cable   3-Cable guides

Remove three silver screws (Call-out 4).
Push the black locking tab (Call-out 5) away from the HVPS, and remove the HVPS.

Figure 6: Remove screws1 - Three silver screws2 - The black locking tab that holds in the HVPS

Removal and replacement instructions for the DC controller

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.

© 2005 Hewlett-Packard