DOWNLOAD Panasonic KX-T7740X (serv.man2) Service Manual ↓ Size: 810.64 KB | Pages: 27 in PDF or view online for FREE

Model
KX-T7740X (serv.man2)
Pages
27
Size
810.64 KB
Type
PDF
Document
Service Manual
Brand
Device
Telephone / DSS CONSOLE
File
kx-t7740x-sm2.pdf
Date

Panasonic KX-T7740X (serv.man2) Service Manual ▷ View online

Pin No.
Terminal Name
I/O Function
I/O Setting
Description
41
R61
I/O
O
LED21
42
R62
I/O
O
LED22
43
R63
I/O
O
LED23
44
R70
I/O
O
KEY/LED-COM4
45
R71
I/O
I
OPEN
46
R72
I/O
I
KEY-IN0
47
R73
I/O
I
KEY-IN1
48
R80
I/O
I
KEY-IN2
49
R81
I/O
I
KEY-IN3
50
R82
I/O
I
KEY-IN4
51
R83
I/O
I
KEY-IN5
52
R90
I/O
I
KEY-IN6
53
R91
I/O
I
KEY-IN7
54
R92
I/O
I
KEY-IN8
55
R93
I/O
I
KEY-IN9
56
RA0
I/O
I
KEY-IN10
57
RA1
I/O
I
KEY-IN11
58
SEL
I
I
A Four-minute Cycle Vcc Connection
59
Vcc
-
-
60
PB0
I
I
Not use GND Connection
61
PB1
I
I
Not use GND Connection
62
PB2
I
I
Not use GND Connection
63
RD0/COMP0
I
Comp
Not use GND Connection
64
RD1/COMP1
I
Comp
Not use GND Connection
10
KX-T7740X-B
8 BLOCK DIAGRAM
KEY
LED
CPU
IC1
CPU RESET
KX-T7740X-B  MAIN BOARD
IC4
CLOCK
OSCILLATOR
X1
SIGNAL
RECIEVING
CIRCUIT
SIGNAL
SENDING
CIRCUIT
Q1,IC2
T1
Q2,IC2
POWER
REGULATOR
IC3
D1
H
L
5V
11
KX-T7740X-B
9 CIRCUIT OPERATIONS
9.1. RESET CIRCUIT
Circuit Operation:
This circuit is used for transmission of a reset pulse to the CPU (IC1) at the following times; connecting the telephone line jack and
during circuit operations. The timing chart is shown below.
Power ON
→ IC4 Pin 1 High Level → IC4 Pin 1 Low Level
12
KX-T7740X-B
9.2. DATA COMMUNICATION CIRCUIT
Function:
The data communication circuit serves the following functions:
Information exchanger between the PBX and DSS console and key input information as well as data for the LED control, etc. This
information is exchanged continuously at all times.
Circuit Operation:
When the DSS console receives an IRQ signal from the PBX, after it sends the key input information (19 pulses) to the PBX and
receives the data (47 pulses) for the LED control, etc. , the DSS console will return an acknowledge signal to the PBX.
1) Reception
The data from the DSS console is received via the H and L line along the path shown below.
H, L Line
→ D1 → T1 → R6 → Q2 → IC2 → IC1 Pin 18
2) Transmission
The data to the DSS console is transmitted along the following path.
IC1 Pin 12
→ IC2 → Q1 → T1 → D1 → H, L Line
13
KX-T7740X-B
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