Lexmark C792de, Service Manual

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Diagnostic aids
3-37
5062
Step 4b: Second transfer
Once the four planes of color are transferred to the transfer belt from the photoconductors, the image is carried
toward the transfer roll, which is also part of the ITU. Based on the speed of the transfer belt, the proper time to
send the signal to pick the paper from an input source is determined. The pick is timed so that the paper passes
between the transfer belt and transfer roll when the image on the belt reaches the second transfer area.
The HVPS 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 paper and the entire image is transferred
from the transfer belt to the paper.
Service tips
•
If the transfer roller has nicks, pits, or flat spots on it, the surface doesn’t come into contact with the
paper and transfer unit properly. This will cause voids or light spots on the page or repeating voids/
light areas.
•
If the transfer roller does not engage the transfer unit, or does not have voltage coming from the
HVPS, 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 HVPS contacts to the transfer roller.