HP 8000dn Service Manual - Page 444

Note 4 To set the power supply switch to Diagnostic Mode, pull the blue power supply switch outward. The motors will start. Paper should now be lifted from the tray and fed through the VTU. The service LED flashes regularly every 0.5 seconds. • If the unit does not work properly, the service LED on the Controller PCA flashes in a pattern that indicates the problem. (See table 7-27 on page 421 for an interpretation of the LED patterns.) 5 To stop the test, set the power supply switch back to Operational Mode. Open the VTU, and remove any media from the paper path. 6 To test Tray 4, close Tray 4 and open Tray 5. Repeat step 4. 7 To stop the test, set the power supply switch back to Operational Mode, and set the DIP switches on the Controller PCA to the off position (see table 7-26 on page 418). Open the VTU, and remove any media from the paper path. 2 x 500-sheet Input Tray Sensor Test This test manually activates the sensors on the 2 x 500-sheet Input Tray to test if they are working properly. 1 Set the DIP switches on the Controller PCA for sensor test mode. (See table 7-26 on page 418 for an explanation of the settings.) 2 To set the power supply switch to Diagnostic Mode, pull the blue power supply switch outward. 3 To manually activate each sensor, press it in with your finger. • When you activate the sensor, the service LED on the Controller PCA comes on. When you release the sensor, the LED goes off. • If the LED does not come on, there is a problem with the sensor. Replace the corresponding field-replaceable unit. 4 To stop the test, set the power supply switch back to Operational Mode, and set the DIP switches on the Controller PCA to the off position (see table 7-26 on page 418). Be sure to turn the power supply off, and set all the DIP switches to the off position (normal settings) when you finish the diagnostics or the printer will not work properly. Replace the back cover. 420 Chapter 7 Troubleshooting EN