FO-3150U/C
Fig. 28
: FAX SENDING/RECEIVING
C
LIU PWB
CONTROL
DG
DG
DG
DG
DG
RTLoop
DG
DG
EXIT
LINE
RX
TX
1, 0
C I
Mi c/
CML
HS-
L PF
0, 1
SIGTX SPKRP
(20438 I/A)
0,
1,0
1,1
0
ect
SIGRX
Mut e,0,- 6, -12dB
C I
T XOUT
SIN
SP Out Enable
LninS el
D A C
HS
0 ,2 0 ,25, 30dB
0, 6dB
MICP
1, 1
S OUT
MICMUTE
A D C
0, 4dB
0, 0
OPAMP
OPAMP
SW1
HOOK-SW PWB
OPAMP
OPAMP
E
B
C
3
5
4
T1
E
B
C
E
B
C
E
B
C
SPMUTE
SPOUT
(H:MUTE)
DETECTOR
+24V
+5V
DG
SPMUTE
DTMFMUTE
TELMUTE
MICMUTE
RCVOL
RHS-
DETECTOR
RXIN
Mic Enable
LINE
OUT
Sel
Line Out Enable
Line In Enable
(H:MUTE)
(H:MUTE)
(Example: Fax signal send)
5 – 24
[5] Circuit description of power supply
PWB
This power supply unit has the function to convert the AC120V (50/60Hz)
to DC24V, and provide these output to the equipment. The following
explains the function of each block. (See Fig. 29)
1. Filter circuit block
This circuit reduces the outgoing noise through the input lines which is
generated in the power supply unit and prevents the invasion of the
noise from the lines.
(The excessive surge such as thunder is prevented by the varistor (Z1).)
2. Rectification and smoothing circuit block
This circuit rectifies and smoothes AC input and provides the DC volt-
age to the switching circuit block.
3. Switching circuit block
This circuit converts the DC voltage (provided from the rectification and
smoothing circuit block) to the high-frequency pulse voltage by FET (Q1)’s
switching (on/off repeat) and provides the energy to the transformer (T1).
It discharges the energy (charged during the FET ON time) to the sec-
ondary side during the FET OFF time through the secondary windings.
The output voltages on the secondary side provided by the energy de-
pend on the ratio of the winding turns (primary : secondary) etc.
4. Control circuit block
This circuit block controls the output voltage by transmitting the detected
24V voltage to the primary control circuit through the photo-coupler (PC1).
In case of the over-current, this circuit reduces providing the energy to
the transformer. In case of the over-voltage, this circuit reduces provid-
ing the energy to the transformer by letting the power-zener (D202 :
connected between the 24VH output voltage and GND) into the short
mode and letting the over-current protection circuit work.
5. 24 VH output circuit block
This circuit block rectifies and smoothes the high-frequency pulse volt-
age provided by the transformer, and provides the DC24V output to the
equipment. The output voltage is adjusted by the variable resistor
(VR101).
6. 24 V output circuit block
This circuit block supplies DC24V output to equipment through a micro-
switch (SW101) from 24VH provided by the transformer.
7. +5 V output circuit block
This circuit block rectifies and smoothes the high-frequency pulse volt-
age provided by the transformer and provides about DC6.5V output to
the regulator IC and provides the DC5V output to the equipment.
8. AC output circuit block
This circuit block supplies AC output from AC input to equipment through
the optical-isolator (PC2) and the power-relay (RL1) by signals (+24V/
HL ON+/PWRLY-).
9. Zero cross circuit block
This circuit block rectifies the AC input, and provides the ZC signal to
equipment through the photo-coupler (PC3).
Summary of Contents for FO-3150
Page 107: ...FO 3150U C 6 9 Control PWB parts layout Top side ...
Page 108: ...FO 3150U C Control PWB parts layout Bottom side 6 10 ...
Page 112: ...FO 3150U C 6 14 TEL LIU and Hook SW PWB parts layout Top side ...
Page 113: ...FO 3150U C TEL LIU and Hook SW PWB parts layout Bottom side 6 15 ...
