Filter
Top Products
33
TTP-248M Bar Code Printer
Service Manual
2. Selecting AUTO RIBBON to detect ribbon will get a value of tension, and then
selecting the MANUAL Ribbon.
When sensor detects ribbon:
LCD displays Not Through the voltage of receiver (PIN 4)≦1.26V
When sensor detects no ribbon:
LCD displays Through the voltage of receiver (PIN 4)≧2.10V.
GND
VCC
8 9
U4D
74HC14
R9
10K
R77
100
REND_SENS
R_END
1
2
3
4
5
JP22
R_SENS
Fig. 3.14 Ribbon End Sensor Circuit
3.12 Serial Port Circuit
C1+
1
V+
2
C1-
3
C2+
4
C2-
5
V-
6
T2OUT
7
R2IN
8
R2OUT
9
T2IN
10
T1IN
11
R1OUT
12
R1IN
13
T1OUT
14
VCC
16
GND
15
U31
SP3232E
C9
0.1u
C10
0.1u
VCC
C11
0.1u
C17
0.1u
GND
GND
L7
BEAD 300
L8
BEAD 300
L9
BEAD 300
L10
BEAD 300
C12
0.1uGND
F1
1A
TX
RX
DSR
RDY
GND
5
9
4
8
3
7
2
6
1
JP3
DB9_1
VDD
VCC
1
RxD
2
TxD
3
GND
4
D+
5
D-
6
R-
7
R+
8
U32
LTC490
GND
VCC
R80
120
R81
120
L13
INDUCTOR1
L14
INDUCTOR1
L15
INDUCTOR1
1
2
JP28
2PIN
L12
INDUCTOR1
U1/168
U1/174
U1/176
U1/170
RxD2/SCPT4
TxD2/SCPT4
CTS2/IRQ5/SCPT7
RTS2/SCPT6
Fig. 3.15 Serial Port Circuit
U18 (SP3232E) is RS232 asynchronous communication driver IC.