Brother HL 1240 - B/W Laser Printer Service Manual page 157

Factory inspection mode
The factory inspection mode is used to check if the sensors in the printer are functioning
correctly. In the process of this inspection, the LEDs and the control panel button are also
checked.
On entering this mode, the LEDs show the status of the respective sensors as shown in the
figure below;
Toner sensor
Rear registration
sensor
Front registration
sensor
Upper paper cassette
sensor (HL-1250 only)
For checking more sensors, press the panel button. The LEDs show the status of the
respective sensors as shown in the figure below.
Drum
Ready
Paper
Alarm
Toner
Data
Drum
Toner sensor
Ready
Rear registration sensor
Paper
Alarm Front registration sensor
Toner
Data
Upper paper cassette sensor
Button unpressed
Fig. 6-12
ON (The toner cartridge is installed.)
OFF (No toner cartridge is installed.)
ON (Paper is detected.)
OFF (No paper is detected.)
ON (Paper is detected.)
OFF (No paper is detected.)
ON (No paper cassette is installed.)
OFF (The paper cassette is installed.)
Paper eject sensor
Lower paper cassette registration sensor
Cover sensor
Button pressed
Fig. 6-13
6-47
CHAPTER 6 TROUBLESHOOTING
(HL-1250 only)
Drum LED ON
Drum LED OFF
Ready LED ON
Ready LED OFF
Alarm LED ON
Alarm LED OFF
Data LED ON
Data LED OFF
(HL-1250 only)