Lexmark C 746 Service Manual

Diagnostic aids3-69
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Developing
The two primary components of the developing process are the photoconductor unit and the toner cartridge. The 
toner cartridge contains a toner adder roll, developer roll and toner. Toner is advanced toward the toner adder 
roll by three paddle assemblies. The advanced toner clings to the electrically charged toner adder roll. The toner 
on the toner adder roll is then electrically attracted to the developer roll because of the difference in...

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Transferring
After the toner is attracted to the photoconductor drum, the image is ready for transfer onto the print media. The 
print media is advanced in the paper path onto the transfer belt and is carried along the belt underneath each 
photoconductor unit. The charged transfer roll(s) located inside the transfer belt pulls the image from the 
photoconductor drum to the print media. This is a direct transfer method.
The main function of the transfer belt...

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Fusing
After the image has been transferred onto the print media, it is ready for fusing. The print media is transported 
into the fuser where the hot roll and backup roll use a combination of high heat and pressure to melt and press 
the toner to the media.
Backup roll
Hot roll 

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Cleaning
The transfer belt and photoconductor drum are cleaned at the end of the electrophotographic process cycle. The 
transfer belt surface is cleaned as it rotates past a cleaning blade and shaft located inside the transfer belt 
assembly. Any waste toner that is scraped off of the belt is collected in the waste toner container located next to 
the belt inside the transfer belt unit.
The photoconductor drum is cleaned by the cleaning blade.
Transfer...

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Electrical interlock
5 V interlock switch
An interlock switch (A) triggered by the front access door disables the +5 V output to the printhead which turns 
off the laser.
24 V interlock switch
The 24 V interlock switch is located at the front-right side of the machine when you open the front door. Opening 
the front door disengages the 24 V interlock switch and cuts the 24 V supply to the system board, HVPS, 
motors, and fuser. Closing the front door...

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Repair information4-1
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4.  Repair information
Safety information
•The safety of this product is based on testing and approvals of the original design and specific 
components. The manufacturer is not responsible for safety in the event of use of unauthorized 
replacement parts. 
•The maintenance information for this product has been prepared for use by a professional service person 
and is not intended to be used by others.
•CAUTION: When you see this symbol, there is a danger...

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Handling ESD-sensitive parts 
Warning:  Read the following before handling electronic parts.
Many electronic products use parts that are known to be sensitive to electrostatic discharge (ESD). To prevent 
damage to ESD-sensitive parts, follow the instructions below in addition to all the usual precautions, such as 
turning off power before removing electronic cards:
•Keep the ESD-sensitive part in its original shipping container (a special “ESD bag”) until...

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Screw and retainer identification table
The following table contains screw types and retainers, locations, and quantities necessary to service the 
printer. Pay careful attention to each screw type location when doing removals. You must install the correct 
screw type in each location during reassembly.
Sizes are as close to actual as possible, as long as the printout is not scaled or resized.
Screw identification table
P/N Screw type Location Qty
10B1580...

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18B0832
(Cont.)Taptite M3 L6 
panheadLaser support plate to lower plate 2
Left camshaft lock assembly to printer frame 2
Left frame assembly to laser support plate 2
Left frame assembly to lower plate 4
Lower plate to left frame assembly 2
LVPS support plate to right plate 4
LVPS to right frame plate and support bracket 5
Motor driver card to EP drive assembly 2
MPF driver cover to right frame 3
Right camshaft lock assembly to printer frame 2
Right frame...