Power on It is important to have the MFP control panel functional as soon as possible in the troubleshooting process so that the MFP diagnostics can be used to assist in locating printing errors. Power-on defects Table 22. Power-on defects or blank display 192 Chapter 7 Troubleshooting C8523-90921 Problem Action Is ac power available at the print engine power receptacle? Verify that power is available. See “Specifications” in Chapter 1. Is the MFP on/off switch set to the on position? Push the switch to the “on” position. Are the print engine fans on? NO YES Touch the display screen to put the MFP in the ready state. Note:
The fan operation is significant because all fans are controlled by the dc controller on the print engine. Fans 1 through 5 operate at full speed for 30 seconds during the WAIT period. Fans 1 through 4 will slow to half-speed, and fan 5 will stop during the STBY period and when the MFP is in PowerSave mode. Make sure that the MFP is not in PowerSave mode. Operational fans indicate the following: 1 ac power is present in the print engine 2 the dc power supply is functional (both 24 vdc and 5 vdc are being generated) 3 the dc controller is functional If the fans are NOT working, troubleshoot using the HP LaserJet 9000 series printer service manual.
If the test is successful, check the control panel cable connections at the back of the control panel and at the back of the print engine.