Panasonic DP-3000 Technical Manual page 23

1.1.13. Line Control Board
The following shows a block diagram of the Line Control Board.
CML
PLS
Line
CML
C5
T2
PC2
Ring
Detector
Telephone
for Auto Receive
PC1
Off-Hook
L : Off-Hook
Detector
H : On-Hook
PC1
PC2
+24V
CML
Q1
PLS
Q2
< LCU >
[DZYNA1435*]
The Ring Detector consists of a photocoupler, PC2 (PC1 for LCE), and its peripheral circuits. The ringing
signal is a half-wave rectifier in the Ring Detector, and transferred through the nCTON signal line to the
IC80 on the SC PC Board. The IC80 observes the signal to distinguish from signals caused by chattering.
The Off-Hook Detector (External Telephone) circuit consists of the photocoupler, PC1 (PC2 for LCE), and
its peripheral circuits. When PC1 detects loop current flow, it emits a Low active output signal (nHKOF) to
the IC80 which monitors it for a specified time. If the IC80 detects no change in the Low signal level, it deter-
mines that the External Telephone is Off-Hook.
HYBSR
Off-Hook
GND Line
Detector
MODEM
Telephone
+5V
nHKOFF 9
+5V
nCTON
L : Ring In 10
API
H : FAX Side
L : Telephone
CMLD 5
H : Make
+24V
L : Break
PLSD 6
Q1
CN7
< MDM >
CN25 CN8
HYBSR
11 11
TCK
PC2 CML
PLS
CML
PC1
Ringing
Detector
10 10
nCTON
Ringer
L : Ring In
PC1
Off-Hook
RMCK
CLK
PC2
7 7
IC2
RMCS
P/S
8 8
Country
Code
RMDT
Q8
Jumper
9 9
JP18~23
+24V
5 5
CML
H : FAX Side
L : Telephone
Q4
CMLD
+24V
6 6
PLS
H : Make
L : Break
Q3
Dial Pulse PLSD
TCK
14 14
Loop Relay TCKD
< LCE > <MDM>
[DZYNA1436*]
23
CML
PC2
Line
MODEM
CML
C5
PC1
Ring
Detector
Telephone
ApI
+24V
CML
PLS
HYBSR
PLS
GND
MODEM
T2
+5V
L : Off-Hook
H : On-Hook
nHKOFF 9
PC2
+5V
nCTON
L : Ring In 10
PC1
API
H : FAX Side
L : Telephone
CMLD 5
Q1
H : Make
L : Break
PLSD 6
Q2
CN7
< LCE > < MDM >
[DZEP000441]