HP 4550 Service Manual - Page 306

Table 7-29 Paper path sensors and switches (continued) Identifier Name Description L PS11 ITB photo sensor M N/A 500-sheet feeder: 1=installed, 0=uninstalled N PS9 Top output tray full sensor 1 Press the [ITEM] key until ENGINE DIAGS PATH SENSORS appears on the front panel. 2 Press the [SELECT] key to activate the test. The front panel will display A through N with a binary value below it. When running this test, make sure the ITB drawer is installed and trays 2 and 3 are removed. In this state the default value on the front panel should be: 0X111111110010, where the x can be either a 0 or 1. If there is any other value, then there is a possible problem. Identify the sensor or switch in the table above and test to see if the value changes. Cassette paper size settings for each tray are described in Table 7-30. Table 7-30 Paper size settings Paper Size Tray 2 Switches (DEF) A4 000 B5 001 Custom (A5) 010 Custom (B5 ISO) 011 Letter 100 Executive 101 Legal 110 No tray installed 111 * These values are the same for Tray 3. Tray 3 Switches (HIJ) 000 001 011* 011* 100 101 110 111 Door sensor test The door sensor test allows service personnel to open and close doors on the printer while watching the sensor status on the front panel. Switches 4 and 5 are in series with each other which causes the value to toggle under identifier A. Once the door sensor test is initiated, the front panel displays the status for each sensor listed in Table 7-31. As a door is opened and closed the state of the sensor changes the indicator values on the front panel. Table 7-31 Sensor status Identifier Name A SW4 and SW5 B SW1 * C SW2 * D SW3 * E Drum detect Description Front and rear door switches ITB drawer switch Toner cartridge door * Drum drawer switch * Detect if a drum cartridge is installed 304 Troubleshooting C7085-90921