HP LaserJet 4 Service Manual - Page 121

Table 5-3 Microswitch Signals Switch SW601 SW602 SW603 SW604 SW605 SW851 SW852 SW853 Description PCA Door Open Sensing Switches (front and rear) Paper Control PCA Test Print Switch Paper Control PCA PC tray (Tray 2) Size Sensing Switches Paper Control PCA PC tray (Tray 2) Size Sensing Switches Paper Control PCA PC tray (Tray 2) Size Sensing Switches Paper Control PCA Lower Cassette (Tray 3) Size Sensing Switches Lower Cassette Lower Cassette (Tray 3) Size Sensing Switches Lower Cassette Lower Cassette (Tray 3) Size Sensing Switches Lower Cassette PC (Tray 2) and LC (Tray 3) Tray Size Sensing System Trays inserted into the printer trigger specific microswitches, which define the tray size (see Table 5-4). Refer to Figure 7-1 for location. Table 5-4 Switch Settings for PC (Tray 2) and LC (Tray 3) Trays Tray Size Letter Legal A4 Executive Tray Not Installed SW603 (Upper) ON ON OFF OFF OFF SW604 (Middle) OFF ON OFF ON OFF SW605 (Lower) ON OFF ON ON OFF Functional Overview 5-9