Lexmark X543 Service Manual

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Step 3: Develop
Once the laser exposes the photoconductor, the high-voltage power supply sends charge to the developer 
roll (C). For each color, the toner cartridge engages the photoconductor so it is in contact with the surface. 
Because of the charge difference between the toner on the developer roller and the electrostatic image created 
by the laser, the toner will attract to the photoconductor only where the laser exposed the surface. 
This process would be similar to using glue to write on a can and then rolling it over glitter. The glitter sticks to 
the glue but won’t stick to the rest of the can.
Service tips
Never touch the surface of the developer roller with your bare hand. The oil from your skin may cause 
a charge differential on the surface, and toner will not stick properly. The result would be repeating 
blotches of voids/light print on a page. Then the affected cartridge will have to be replaced.
If the developer roller is damaged, it will not contact the surface of the photoconductor properly. The 
result could be repeating marks, thin vertical voids, or thin vertical lines of color on the printed page. 
Check the surface of the developer for damage. 
						

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Step 4a: First transfer
When the latent images are developed on each Photoconductor, the high-voltage power supply sends voltage to 
the 1st Transfer Rollers inside the ITU (D). 
The charge difference between the developed toner image on the Photoconductor surface and the 1st Transfer 
Roller causes the images to transfer to the surface of the ITU belt for each color. This takes place by a direct 
surface-to-surface contact between the Photoconductors and the ITU belt. 
Service tips
Never touch the surface of the ITU belt with your bare hand. The oil from your skin will cause a charge 
differential on the surface, and toner will not stick properly. The result would be repeating blotches of 
voids/light print on a page. Then the ITU belt will have to be replaced.
Don’t use solvents or other cleaners to clean the ITU belt surface. No matter how careful you are, the 
surface will be compromised, causing scratches or a charge differential that will produce a void or 
light blotch on the printed page. Then the ITU belt will need to be replaced. 
						

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Step 4b: Second transfer
Once the four planes of color are transferred to the transfer belt from the photoconductors, the image is carried 
towards the transfer roll (E). This transfer roll is also part of the ITU. Based on the speed of the transfer belt, the 
proper time to send the signal to pick the media from an input source is determined. The timing of the pick is 
such that the media reaches the point where the transfer belt and transfer roll meet. The paper passes between 
the transfer belt and transfer roll when the image on the belt reaches the second transfer area.
The high-voltage power supply sends voltage to the transfer roll (E) to create a positive charge. Once the image 
on the transfer belt reaches the transfer roll, the negatively charged toner clings to the media and the entire 
image is transferred from the transfer belt to the media. 
Service tips
If the transfer roller has nicks, pits, or flat spots on it, the surface doesn’t come into contact with the 
media and transfer unit properly. This will cause voids or light spots on the page or repeating voids/
light areas, because the toner can’t be fully transferred due to the charge difference in the areas of 
damage.
If the transfer roller does not engage the transfer unit, or does not have voltage coming from the high-
voltage power supply, the toner will not fully transfer from the transfer unit; the entire page will be very 
light or blank. Any toner that does transfer will be due to a “contact” transfer instead of a “charge” 
transfer. Check the high-voltage power supply contacts to the transfer roller. 
						

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Step 5: Fuse
Once the image has been fully transferred to the media, the transfer roll helps move the paper into the fuser 
area.
The fuser (F) applies heat and pressure to the page to melt the tiny toner particles and bond them permanently 
to the media. The fuser moves the paper to the redrive rolls which move the paper to the output bin.
Service tips
If the fuser rollers are damaged, they can cause toner to be pulled off the page or cause paper jams.
Toner that rubs off a printed page can be a sign of a malfunctioning fuser or an improper media 
setting. Always check the paper type setting before replacing the fuser. A common mistake is to print 
on heavier media (such as cardstock) with the paper type set to plain paper.
When removing paper jams from the fuser, be sure to use the fuser release tabs to relieve the 
pressure on the page. In addition, never pull unfused toner through the fuser if you can help it; try to 
back the jammed page out of the fuser in the opposite direction it was travelling. 
						

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Step 6: Clean/Erase
There are two main cleaning processes that take place during the EP Process. One process cleans the transfer 
belt, and the other cleans the photoconductors.
Transfer Unit Clean
Once the toner image on the transfer belt has been transferred to the page, the transfer belt rotates around and 
is cleaned by the cleaning blade (G). This occurs for every page that is printed.
After the toner is moved to the cleaning blade, the toner is moved from the cleaning blade (G) to the waste toner 
area using an auger system. 
						

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Photoconductor Clean/Erase
After each plane of color has been transferred to the transfer belt from the photoconductors, a cleaning blade (H) 
scrapes the remaining toner from the surface of each photoconductor.   This is the clean/erase process.
Now the photoconductor surface is prepared to begin the EP cycle once again. This cleaning/erasing cycle 
happens after each plane of color is transferred to the transfer belt. 
						

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Paper path, transport components
In order for an image to be printed, the media has to be moved from an input source (such as a tray) into the 
printer and eventually exit into an output source. 
The most important component in this process is this media itself. Old, damaged, or out-of-specification media 
can and will cause feed and transport problems. If you encounter problems, you should always check the media 
first “Media guidelines” on page 1-13. In addition, it is always good practice to check the printer and driver 
settings to see if the media being used matches the user’s settings. It is not uncommon to find a user printing on 
cardstock with the printer programmed to print on a plain paper setting.
The printer’s feed and transport components can fail and cause paper jams or other feed and transport 
problems. These components should be examined for damage or wear and replaced if necessary. 
Below is a summary of the paperpath, and transport components.
Paper path Information
The MFP has a simple “C” shaped paper path (see the picture below).   The paper paths are shown in red. 
Paper is fed from the bottom of the printer from the paper tray, or manual feed, and travels upward through the 
front cover.
There is a duplex unit on this MFP. The duplex unit is built into the front cover and drawer 1. Duplexing is 
described later. 
						

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Transport components
In summary, the media is fed from the tray into the printer by a feed roll and carried to the transfer roll (ITU). The 
pick rollers time the media to enter the EP process at just the right moment.
The pick rollers push the media to the ITU where the image is transferred to the page. 
The transfer roller moves the media to the fuser where heat and pressure are applied to the page. The fuser 
rollers push the media toward the exit bin and past the exit sensor. The exit rollers guide the paper into the 
output bin.
Note:  If the printer posts a paper jam message but no paper is found, paper dust or paper particles may have 
fallen in one of the sensor eyes. Use a can of compressed air to gently clean the sensor.
Duplexing (models with duplex support only)
The MFPs with duplex support use a secondary paper path in the front cover and the 250-sheet paper tray to 
print on the second side of a sheet of paper. The following steps summarize the duplexing process.
After the first side of the media is printed and the trailing edge of the paper clears the fuser exit sensor, the fuser 
motor reverses. The reversed motor pulls the media into the duplexer paper path. In addition to the fuser motor 
reversing, the pick motor also reverses. The pick motor drives the duplex aligner rolls (A) which push the media 
down to the bottom turnaround in the paper tray and gate aligner (B). 
Note:  While the sheet is being transported through the front door and paper tray, it is the only piece of media 
being processed by the print engine. A user should not attempt to insert a piece of media into the manual paper 
feed while a duplex job is being processed. This would invoke a paper jam error. 
						

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When the trailing edge of the media clears the fuser, the fuser engine rotates forward to prepare the fuser for the 
page travelling through the duplexer.
As the media reaches the gate aligner, a sensor (S1) is triggered indicating the presence of the leading edge.
When the S1 sensor is triggered, the paper continues to the S2 sensor. When the S2 signal is detected, the 
speed of the paper is adjusted to accommodate the speed of the transfer belt, ensuring the proper registration of 
the image on the media. The paper travels to the ITU (C) and the second image is transferred to the reverse side 
of the media.
Once the imaged is transferred, the media travels to the fuser (D), the fuser exit rolls (E), and the output bin. 
						

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Scanner theory
Duplex ADF
The following illustration shows the paperpath, rollers and sensors used in the X544 duplex ADF.
The X544 duplex ADF enables the user to create duplex scans automatically, eliminating the need to stop the 
scanning process to flip the media being duplicated over. The ADF uses a step motor, and a series of sensors to 
determine the media’s position in the paper path during the scan process. 
The following steps are performed in creating a duplex scan on the X544 duplex ADF. 
1. The scanner control unit, on the controller board receives a command to create a scan, fax, or copy. 
2. A signal is sent to the ADF to poll the paper present sensor to check if the media to be scanned is in the 
correct position. The media must be placed in the ADF input tray so it actuates the paper present sensor. If the 
ADF paper present sensor isn’t actuated, a flatbed scan is run by default.
3. If the media has actuated the paper present sensor, an ADF scan is executed. At this point the roller on the 
pick arm assembly drops and advances the paper into the ADF, actuating the document sensor. Actuating this 
sensor determines that this will be the first side of the document to be scanned. 
4. When the document sensor is actuated, a signal is sent to flatbed to move the CCD imaging unit to the ADF 
scan area. When the CCD reaches the ADF scan area, a calibration is performed on the CCD. 
5. The media is advanced to ADF scan sensor which is located by the takeaway roll. If the paper does not reach 
the ADF scan sensor in a predetermined length of time a jam error will be generated. 
6. When the ADF scan sensor is actuated the paper advances to the scan area. While the paper is advancing to 
the scan area, the ADF motor generates pulses which are stored in an on-board counter. These counts along