Diagnostic Information; Power-On Self Test (Post) Sequence; Theory Of Operation - Lexmark S800 Series Service Manual

Lexmark S800 Series

2. Diagnostic information

Power-On Self Test (POST) sequence

Plug the All-In-One into an electrical outlet. The printer comes on automatically.
The All-In-One does a Power-On Self Test (POST) sequence.
1. The Power button, Copy button, and Color button lights come on.
2. The following will be displayed on the LCD screen sequentially:
Lexmark, Energy Star, and a bar indicating the remaining time for POST.
3. The purge pump runs simultaneously, and then shuts off.
4. The carrier moves off of the maintenance station simultaneously, and then returns.
5. Home Menu appears on the LCD screen with functional icons.
If any of these fail to occur, remove and reinstall the print cartridge, and then repeat the POST. If the POST remains
"Service checks" on page
incomplete, then see

Theory of operation

The printhead system consists of a single ½"chip with 640 nozzles per color. The ink is supplied and stored in individual
felt-filled ink tanks. Upon installation of the tanks, the ink must be drawn from the tanks to the printhead chip. This is
accomplished by activating the pump to create a vacuum in the maintenance cap. The vacuum is held until all air is
purged from the ink system.
Media is loaded into the input tray where it is restrained by the friction buckler. The edge guides are adjusted to center
the media and ensure that it sits squarely in the tray. The media sensor detects media type (plain, photo, coated,
transparency) or paper-out. When a print job is received by the printer, an authentication and maintenance operation is
invoked. During this operation, the validity of the tanks and the ink level in each tank are verified by the RFID system.
The printhead is then prepared for printing by wiping the surface of the chip and activating each nozzle.
The printing operation is initiated as the pick roll, which is driven by the pick motor, applies a lateral force to the top
sheet of the media. This force overcomes the resisting force of the friction buckler, allowing the single sheet to be
separated from the remaining media stack. The pick roller moves the media sheet to the feed roller, which hesitates to
rotate until sheet is squared with nip. This corrects for skew. The pick roller is de-energized and now the feed roller
advances the media to the print zone. The printed image is applied in horizontal swaths as the carrier drives the
printhead across the page. Successive swaths are overlaid by repeatedly incrementing the feed roller a set distance
between print swaths. The printed media is driven out of the print zone by a nip formed by a driven exit roller and fine-
pointed starwheels.
If a duplex print job is selected, the media is not fully exited from the machine after the first side is printed, but is driven
just far enough to clear the upper duplex gate. At this point the pick motor is driven in reverse which lifts the upper
duplex gate. The feed roller is then driven in reverse and the media is fed into the duplex guides where it is driven by
the duplex roller. After the page is rotated in the duplexer, it arrives back at the now forward-rotating feed roller and the
second side is printed.
2-1
Service Manual
2-13. Find the symptom, and take corrective action.