Brother HL-4040CN Service Manual page 301

Life of Drum Unit
<How to read the drum unit life>
- It initially indicates 100% and gradually decreases.
- It indicates 0% when the "Drum End Soon" appears on the LCD.
- It stays at 0% even if further printing is done.
<How to calculate the drum unit life>
The drum unit life is based on the "drum counter" or the "number of drum rotations".
The drum counter is based on the total printed pages on each drum unit. This total printed
pages should be reset every time you replace the drum unit with a new one. (Refer to
Parts Life Reset Function" in Chapter
printable pages of the drum unit.
If the developing bias voltage correction or color registration adjustment is performed
frequently, however, only the number of drum rotations increases, and the "page counter
based on the number of drum rotation" exceeds the "drum counter" based on the total
printed page.
Refer to the calculation of the drum unit life based on the number of drum rotation below;
<How to calculate the page counter>
The number of drum rotations for the first page printed is about 27. The number of drum
rotations per one page for the second or later page printed (continuous printing) is 4.6.
Using these figures, the page counter is calculated as follows:
Page counter based on the number of drum rotations = (Number of drum rotations for the
first page printed + (Number of drum rotations per one page for the second or later page
printed x (Number of pages in continuous printing - 1))) / 27
(* The number of drum rotations per one page continuous printing.)
Example: Starts to print when the machine is in the Ready state.
Continuous printing
1 page/job
2 pages/job
18 pages/job
If you leave the machine without printing for a long time, the number of drum rotations is
increasing because the developing bias voltage correction and the color registration are
performed. If you print one page per one job every time after leaving the machine without
printing for a long time, the drum unit life is shorter than usual.
The number of drum rotations required for the developing bias voltage correction = 40
rotations.
Example: Performs the developing bias voltage correction and starts to print after leaving
the machine without printing for a long time.
Continuous printing
1 page/job
2 pages/job
18 pages/job
2.) Basically this amount is equal to the assured
Page counter based on the number of drum rotations (Pages)
(27 + (4.6 x (1 - 1))) / 27 = 1
(27 + (4.6 x (2 - 1))) / 27 = 1.17
(27 + (4.6 x (18 - 1))) / 27 = 3.89
Page counter based on the number of drum rotations (Pages)
(40 + 27 + (4.6 x (1 - 1))) / 27 = 2.48
(40 + 27 + (4.6 x (2 - 1))) / 27 = 2.65
(40 + 27 + (4.6 x (18 - 1))) / 27 = 5.37
5-31
"2.3
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