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[3] Circuit Description of TEL/LIU PWB
(1) TEL/LIU block operational description
1) Block diagram
H
L
L1
CURRENT
SENSOR
SPEAKER
~
TAX
PULSE
FILTER
L2
DUMMY
L&C
T1
SHUNT
CIRCUIT
CI DETECTOR
~
–
+
E
SPARK
QUENCH
ACTIVE
CHOKE
CNLIU-10
CNLIU-8
CNLIU-7
CNLIU-9
CNLIU-20
CNLIU-13
CNLIU-22
CNLIU-18
N.C.
N.C.
N.C.
MPX A
DP
E-RLY
CML
HS
CNLIU-24
CNLIU-23
CNLIU-19
N.C.
N.C.
N.C.
X2
X1
X0
H
L
CNLIU-3
CNLIU-1
CNLIU-12
CNLIU-2
CNLIU-5
CNLIU-4
CNLIU-6
CNLIU-14
CNLIU-21
CNLIU-15
DG
+5V
+12V
AG
SPMUTE
DG
+5V
+12V
AG
AG
DG
DT3
DT
CI
VOLA
VOLB
BZOUT
RHS
DP
SDT
HS1
RXIN
TXOUT
SPMUTE
VRSEL2
VRSEL1
MPX B
MPX A
VOLCNT
TELMUTE
CML
CPU
MODEM
GATE
ARRYA
SPOUT
CI
DPMUTE
H
L
H
L
CNLIU-16
CNLIU-17
SIGTX
SIGRX
H
L
H
L
H
L
L
H
H
L
T2
S
T2
T1
CONTROL PWB
TEL/LIU PWB
SPOUT
Fig. 8
2) Circuit description
The TEL/LIU PWB is composed of the following 12 blocks.
1. Surge protection circuit
2. Noise filter
3. On-hook status detection circuit
4. Dial pulse generation circuit
5. CML relay
6. Matching transformer
7. Hybrid circuit
8. Speaker amplifier
9. Adjustment of voice volume
10. Signal selection
11. Cl detection circuit
12. Power supply and bias circuit
3) Block description
1. Surg Protection circuit
This circuit protects the circuit from the surge voltage occurring on
the telephone line.
•
The AR1 protects the circuit from the 390V or higher line surge
voltages.
•
The VA1 and VA2 protect the circuit from the 470V or higher
vertical surge voltages.
•
The ZD4 and ZD5 control the voltages generated on the sec-
ondary side of matching transformer to 2V.
•
The VA3 protect the circuit from 100V or higher line surge
voltages.
2. Noise filter
The noise filter comprises the RF choke coil, L1, L2, L3 and
capacitor C16.
•
The L1, L2, L3 and C16 prevent unnecessary radio noises from
being transmitted from the telephone line.
•
The C16 prevent radio pickup from the telephone line.
FO-4500H
5 – 19
Содержание FO-4500
Страница 16: ...M E M O FO 4500H 1 14 ...
Страница 129: ...Control PWB parts layout Top side 6 11 FO 4500H ...
Страница 130: ...Control PWB parts layout Bottom side 6 12 FO 4500H ...
Страница 133: ...TEL LIU PWB parts layout 6 15 FO 4500H ...
Страница 134: ...6 16 FO 4500H ...
Страница 136: ...Power supply PWB parts layout 6 18 FO 4500H ...
Страница 141: ...M E M O 6 23 FO 4500H ...
Страница 149: ...Scanner unit Fig 6 Optical adjustment tool Fig 7 Fig 8 FO 4500H 8 6 ...