Lexmark X543 Service Manual

Diagnostic aids3-49
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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....

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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...

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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...

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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...

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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...

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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...

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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...

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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...

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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...