Lexmark C 746 Service Manual
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Diagnostic aids3-49 5026 Go Back Previous Next 240 paper jam If paper is jammed in Tray 1, 241.xx Paper jam appears. If paper is jammed in any of the optional trays, 24x.xx Paper jam appears. •If the jammed paper is located in tray 1, follow these steps to remove the paper from tray 1. 1.Open tray 1, and pull the jammed pages straight up and out. 2.If the jam is located in front of the tray, pull the jammed pages up and out. 3.After removing the tray, the front door may need to be opened to access the jam. 4.Close tray 1. 5.Press or touch . •If the jammed pages are located in one of the optional trays, follow the appropriate steps below to remove the pages from an optional tray. 1.Open the specified optional tray, and pull the jammed pages out as illustrated. 2.After removing the tray, the tray above may need to be opened to access the jam. 3.Close the specified optional tray. 4.Press or touch .
3-50Service Manual 5026 Go Back Previous Next 250 paper jam If paper is jammed in the multipurpose tray, 250.xx Paper jam appears. 1.Press the paper release lever, and then remove the jammed pages from the multipurpose tray. 2.Load new paper into the multipurpose tray. 3.Press or touch . 1 2
Diagnostic aids3-51 5026 Go Back Previous Next Theory of operation Paper path
3-52Service Manual 5026 Go Back Previous Next Main Components System board The system board provides the intelligence of the printer. Command and control signals originate in the system card that make print media travel possible. The system card controls the timing of the print media during the printing so the media arrives at certain positions in the print process at certain times. Paper tray Houses the print media. Paper pick mechanism Picks the print media from the paper tray. The paper pick mechanism contains the paper pick (input) sensor and the multifunction transparency sensor. Bump aligner roll The bump aligner roll advances the print media onto the transfer belt and corrects any media skew as it comes out of the paper trays or MPF. Transfer belt The transfer rolls (located inside the transfer belt unit) are an integral part of the electrophotographic process, and the transfer belt advances the print media through the printer. Fuser The fuser bonds toner to the print media and advances the print media through the last portion of the paper path. The paper exit sensor is also located in the fuser, and a flag is present on all fusers that activates the bin full sensors on network model printers. Duplex The duplex function is built into the front access door and uses a two-pass method for rerouting the paper down and back through the paper path for a second time. To accomplish the two-pass method, the paper is fed partially out of the printer and is then reversed back into the printer.
Diagnostic aids3-53 5026 Go Back Previous Next Print media transport The print media is picked from the input source and fed to the bump aligner roll. The media movement is detected by a sensor located in the paper pick mechanism. It does not matter where the media comes from (Tray 1, Tray 2, or, the MPF); it will enter the electrophotographic process at the bump aligner drive. The bump aligner motor drives the bump aligner roll which feeds the paper to the transfer belt. 500-sheet assembly pick tireBump aligner roll MPF pick tire Pick tire Backup aligner roll
3-54Service Manual 5026 Go Back Previous Next Once the paper is fed onto the transfer belt, the photoconductor drums in conjunction with the transfer belt pull the print media through the paper path. Photoconductor drums Transfer belt
Diagnostic aids3-55 5026 Go Back Previous Next Once the print media exits the transfer belt, it enters the fuser where heat and pressure are applied to bond the toner permanently to the media. The fuser rollers continue to turn and pull the print media through the paper path until it reaches the exit drive roll. The exit drive roll pulls the print media from the fuser rollers and delivers it to the fuser output drive roll. Once the print media reaches the fuser output drive roll, the roller pushes the print media into the output bin. Fuser output drive rollFuser exit drive roll Paper exit flagFuser backup roll Fuser exit idler roll Fuser hot roll
3-56Service Manual 5026 Go Back Previous Next If the page is to be duplexed, the fuser output drive roll continues to pull the media until it clears the paper exit flag and then reverses the rotation of the roller in order to pull the media back into the printer duplex assembly. The media is then routed down through the duplex path until it reaches the bump aligner roll. Once in this position, it enters the EP path for the second time. The paper exit flag serves two purposes. When it triggers the paper exit sensor, it serves as a one-way gate for the media when it is exiting the printer to the output bin and also serves as a one-way gate when the media is entering back into the printer for a duplex print. In other words, it diverts the print medias path, directing it to either the output bin or the duplex paper path. Fuser output drive roll Paper exit flag
Diagnostic aids3-57 5026 Go Back Previous Next Mechanical drive In order for the print media to move through the paper path, there are several drive motors that supply the mechanical power to the rollers discussed previously. The drives for these components are illustrated and discussed in the following paragraphs. Paper pick mechanism drive When printing from Tray 1 or Tray 2, the paper pick motor drives the paper pick gears which causes the pick roller to turn. During an MPF print, the paper pick motor drives the swing arm assembly for the MPF and causes the MPF paper pick roller to turn. Swing arm bracket (C52x) MPF swing arm assembly Paper pick mechanism gears Paper pick motor Paper pick mechanism Paper tray and paper pick mechanism shown from rear with components removed for clarity MPF paper pick
3-58Service Manual 5026 Go Back Previous Next Bump aligner drive The power to turn the bump aligner roll is supplied from the bump aligner motor. The motor drives a set of bump aligner gears which causes the bump aligner roll to turn. Note: If this motor is stalling or causing waste toner box full messages, the vertical auger mechanism might be causing the problem. Bump aligner roll Bump aligner gears Bump aligner gears Bump aligner motor