HP 8000dn Service Manual - Page 160

Printer Input Sources Paper Size Switches The paper guides in Trays 2 and 3 operate four levers at the back of the trays that activate the size sensing switches (SW1601 through SW1604) mounted in the printer chassis. Paper sizes are compared to switch conditions in table 5-6. Table 5-6. Paper Size Switches Paper Size SW1601 Ledger (portrait) OFF A3 (portrait) OFF B4 (portrait) ON Legal (portrait) ON Letter (landscape) OFF A4 (landscape) OFF SW1602 OFF ON OFF ON OFF OFF SW1603 OFF OFF OFF OFF OFF ON SW1604 OFF OFF OFF OFF ON OFF Printing from Trays 2 and 3 The Pickup, Feed, and Separation rollers start rotating when the DC Controller receives the /PRNT signal from the Formatter PCA. Then, the DC Controller activates the Pickup Solenoid (SL1) and starts feeding paper through the Paper Input Unit (PIU), triggering photosensors PS2 and then PS1. These sensors inform the DC Controller that paper has passed through the PIU and is present at the Registration Assembly. When the Laser/Scanner and Fuser are ready, the DC Controller sends the /VSREQ signal to the Formatter. When the Formatter has processed the print data, it sends the /VSYNC and /VDO signals to the DC Controller. The paper is then released from the Registration Assembly (by CL1) and fed to the photosensitive drum, starting the image transfer and fusing processes. After the paper passes through the Fuser, it triggers PS1403 and PS1402 to the specified type, size, and destination of the paper being fed through the printer. 136 Chapter 5 Functional Overview EN