2-8 Phaser 7750 Printer Service Manual
Fuser
The fuser receives its drive from the main motor. After the toner images are applied to
the paper, the paper is then passed through the fuser. The fuser belt is pressed against
the heat roller to melt the toner and bond it to the paper.
The fuser belt is always spring loaded against the heat roller, but can be released for
jam clearance. The flexibility of the belt (versus a pressure roller) provides a longer
contact time and a larger area of contact with the heat roller, thereby providing better
fusing.
Fuser Life Expectancy
The life expectancy of the fuser is 60,000 letter/A4 size pages. Several factors can
reduce the life of the fuser:
■ Greater than 5% coverage
■ Paper use larger than letter size
■ Printing on heavy media
■ Printing short-edge feed
■ Printing on transparencies or specialty media
Three fuses on the fuse board in the fuser assembly are used in conjunction with a
PostScript algorithm to determine the life used. Fuses are blown in the reverse order
than they were on the Phaser 7700 (3,2,1 instead of 1,2,3). Fuse #3 is blown after 100
prints are made. Fuse #2 is blown at 50% of life and fuse #1 is blown at 99% of life
used.
If fusers are swapped between printers and don’t have the exact same configuration of
blown and closed fuses the printer will make a fuser life assumption based on which
fuses are closed and then set the fuser life using that assumption after 100 prints are
run. All fuses closed, new fuser. Fuse 3 open, fuse 2 and 1 closed, life will be set at
25% used. Fuse 3 and 2 open fuse 1 closed, life will be set at 75% used. All fuses
open, life is set at 99% used.
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