Lexmark C 540n, Service Manual

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Service Manual
5025-2xx, 4xx
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). The 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 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 roll 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 lights 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 roll 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 transfer roll clutch and the high-voltage power supply contacts to the transfer roll.