HP LaserJet 4250 Service Manual - Page 136
Fuser/delivery block, Jam detection,
View all HP LaserJet 4250 manuals
Add to My Manuals
Save this manual to your list of manuals |
Page 136 highlights
Fuser/delivery block The pickup-and-feed system is divided into two blocks: the pickup-and-feed block and the fuser/ delivery block. Figure 5-9 Pickup-and-feed and fuser/delivery block diagram 1 Fuser/delivery block 2 Pickup-and-feed block The fuser/delivery block consists of rollers, sensors, the fuser, and the output delivery assembly. The rollers transport the media through the fuser/delivery block paper path. The fuser applies heat and pressure to the media to permanently bond the toner image to the media. The output delivery assembly sends the printed media either to the rear output bin (if the rear output door is open) or to the top output bin (the default output delivery bin). Sensors along the paper path detect media movement, jams, and the top output-bin capacity. Jam detection The printer uses the followng sensors to detect the presence of media and to verify whether media is being fed correctly or has jammed. For information about the location of these sensors, see Printer switches and sensors. ■ Pre-feed sensor (PS102) ■ Top-of-page sensor (PS103) ■ Fuser-delivery sensor (PS108) The microprocessor on the dc controller PCA checks for jams by timing the media as it moves past these sensors. If the media does not pass the sensor in a specific period of time, the transport process is stopped (motors are turned off and the rollers do not rotate) and a jam message appears on the control-panel display. 122 5 Theory of operation