Brother MFC-J3520 Service Manual page 294

(3) Change the detecting conditions (e.g., insert paper through the registration sensor,
open the ink cartridge cover or document scanner, or remove the ink cartridges),
and then check that the indication on the LCD changes according to the sensor
states.
(4) Press the X key to stop this operation and return the machine to the initial stage of
the maintenance mode.
Magenta ink cartridge detection sensor
ADF cover sensor
Second side document
scanning position sensor
Document scanning
position sensor
Document detection
sensor
Document width
sensor
Switchback sensor
High temperature detector in the complex IC (for main PCB)
Yellow ink cartridge detection sensor
Cyan ink cartridge detection sensor
Magenta ink remaining sensor
Head thermistor
Registration sensor
Black ink cartridge detection sensor
Purge cam sensor
Document scanner sensor
Fig. 5-1
5-23
Black ink remaining sensor
Yellow ink remaining
sensor
Cyan ink remaining sensor
Ink cartridge cover sensor
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