Brother TD-4000, Service Manual

Page: 22 / 139

II - 15
2.3.5 Media Position Detect Sensor Circuit and Cover Open Sensor Circuit
(1) Media position detect sensor circuit
When performing printing and FEED motion through the process described in
subsection 2.3.4 (2) "Media feed motor driver circuit", the CPU reads the sensor
value to detect the medium position.
The CPU receives the voltage of the media position detect sensor (transmission
type photo sensor) sent through CN13 and input it through SENTAN (80 pin).
The CPU processes this voltage through AD conversion and inspects between
label that stays on the sensor position.
Figure 2.3-6 Media Position Detect Sensor Circuit
(2) Cover open sensor circuit
TD-4000/4100N has the cover open sensor. It identifies open/close of the top
cover ASSY from the status of mechanical switch.
Opening the top cover ASSY, the contact of cover open sensor on SB PCB opens.
The change of status is sent as the signal through CN16 to COVER (34 pin) of the
CPU.
The CPU detects open/close of the cover from the change of voltage at 19 pin.
The CPU stops all performances if detecting cover open during printing, FEED or
CUT.
Figure 2.3-7 Cover Open Sensor Circuit