Brother MFC-8510DN, Service Manual

Page: 61 / 373

2-16
Confidential
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Life of drum unit
<How to read the life of drum unit>
• The band graph indicates 100% initially, and then gradually decreases.
• When the band graph indicates 10%, the machine displays a message prompting the user
to replace the drum.
<How to determine the end of life of drum unit>
The end of life of the drum unit is determined based on the "drum counter" or the "number of
drum rotations", whichever is larger.
The drum counter is based on the total number of pages printed on each drum unit. The drum
counter must be reset every time you replace the drum unit with a new one (refer to <How to
reset drum counter> on the
next page ). Basically, the counter value is equal to the assured
number of printable pages of the drum unit. However, if the power switch is turned ON/OFF
frequently or the number of pages printed per job is small, only the number of drum rotations
increases, and the "page count based on the number of drum rotations" may exceed the "drum
counter" based on the total number of pages printed.
Calculation of the page count based on the number of drum rotations shown below.
<How to calculate the page count>
The number of drum rotations for the first page: 12.2
The number of drum rotations per page for the second page and later (continuous printing): 3.8
Page count based on the number of drum rotations = {Number of drum rotations for the first
page + [Number of drum rotations per page for the second page and later x (Number of pages
in continuous printing - 1)]} / 15
(The divisor "15" is assumed value of the number of drum rotations per page when end users
use machines.)
(The number of drum rotations per page is fewer in continuous printing.)
When warm-up operation after power ON or opening/closing cover, paper tray lift-up
operation, or fuser unit warm-up operation is performed, the number of drum rotations
increases. Therefore, if these operations are performed frequently, the life of the drum unit
becomes shorter than usual.
The number of drum rotations required for warm-up operation after power ON: 15
Example: Start printing when machine is in ready state
Continuous pages printed Page count based on number of drum rotations (pages)
1 page [12.2 + {3.8 x (1 - 1)}] / 15 = 0.8
2 pages [12.2 + {3.8 x (2 - 1)}] / 15 = 1.1
18 pages [12.2 + {3.8 x (18 - 1)}] / 15 = 5.1
Example: When warm-up operation after power ON or opening/closing cover is performed
before printing
Continuous pages printed Page count based on number of drum rotations (pages)
1 page [15 + 12.2 + {3.8 x (1 - 1)}] / 15 = 1.8
2 pages [15 + 12.2 + {3.8 x (2 - 1)}] / 15 = 2.1
18 pages [15 + 12.2 + {3.8 x (18 - 1)}] / 15 = 6.1