Brother DCP-L8400CDN Service Manual page 438

1.3.28 Sensitivity adjustment of density sensor (Function code 72)
<Function>
This function is used to print the patch data for density sensor sensitivity adjustment on the
belt unit and measure the density with the density sensor. The characteristics of the density
sensor are calculated based on the value measured by the density sensor, and the parameter
for correcting developing bias voltage is adjusted.
<Operating procedure>
(1) Press the 7 and 2 keys in this order in the initial state of the maintenance mode. "PLS
WAIT 72" is displayed on the LCD and performs the sensitivity adjustment of the density
sensor.
(2) When this operation is completed without errors, the machine returns to the initial state of the
maintenance mode.
Note:
If the sensitivity adjustment of the density sensor fails, "ERROR 72" is displayed on the
LCD. Display the error message by pressing the
that corresponds to the error message.
Error message
dens_l_drk_err
belt_err
dens_pat_err
dens_calc_err
dens_led_adj_err
lph_calc_err
TONER EMPTY #
Cover is Open
Replace Toner
* # indicates the toner color (Y, M, or C) of which cartridge became empty.
- Reconnect the harness of the eject sensor PCB.
- Replace the registration mark sensor unit.
- Replace the main PCB ASSY.
- Replace the belt unit.
- Replace the waste toner box.
- Replace the registration mark sensor unit.
- Replace the main PCB ASSY.
- Check if the toner cartridges are set in the correct order of colors.
- Replace the toner cartridges and drum unit.
- Replace the registration mark sensor unit.
- Replace the main PCB ASSY.
- Replace the belt unit.
- Replace the waste toner box.
- Replace the registration mark sensor unit.
- Replace the main PCB ASSY.
- Replace the toner cartridges and drum unit.
- Securely close the front cover.
- Wipe the scanner window of the laser unit with a soft lint-free
cloth.
- Re-assemble the laser unit.
*
Replace the empty toner cartridge and press the Mono Start key
to clear the error. Perform the sensitivity adjustment of the density
sensor again.
Close the front cover.
Replace the black toner cartridge and press the Mono Start key to
clear the error. Perform the sensitivity adjustment of the density
sensor again.
5-54
key, and take the following measure
Measure
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