HP 4300 Service Manual - Page 112

Printing from the 1,500-sheet feeder The paper-feeder driver controls the operation sequences of the 1,500-sheet feeder. An 8-bit microprocessor in the paper-feeder driver controls the 1,500-sheet feeder sequences and the communication with the DC controller PCA. The paper-feeder driver drives the solenoid in response to the pickup command. The paperfeeder driver also returns the status of the paper feeder to the DC controller PCA. The printer delivers a charge of +24 vdc to the 1,500-sheet feeder, which then generates +3.3 v for the integrated circuits. Figure 24. Note 1,500-sheet feeder I/O block diagram 1,500-sheet feeder pickup and feeding Three switches on the paper-feeder driver detect the media size and the presence of the 1,500sheet tray. The relationship between the switch combinations and the paper sizes is the same as for the printer. See table 32 on page 83 The main motor (M101) of the printer drives the paper feeder. When the DC controller PCA sends a print command the main motor of the printer begins to rotate. When the scanner motor reaches its prescribed speed, the paper-feeder driver receives the pickup command from the DC controller PCA and activates the paper pickup solenoid. (The main motor drives the pickup roller, feed roller, and separation roller.) The pickup roller, activated by the solenoid, rotates once, picking up the media inside the 1,500-sheet tray. The separation roller removes any unnecessary sheets and the media travels to the pre-feed sensor (PS102). The sheet then reaches the registration assembly, where its skew is corrected. Then it goes through transfer, separation, and fusing stages; passes through the delivery unit; and is delivered to the output bin. The 1,500-sheet feeder detects pickup and feed jams in the same way as the printer. See"Printer jam detection" on page 87. 92 Theory of operation Q2431-90912