Sanyo SFX-33 Service Manual page 50

Circuit Description
Power Supply Circuit (M7)
Forward type switching regulator.
output
+24V .................................................................................. NCU (Network control unit).
+24V ................................................................................... Pulse motor (Transmit & Receive)
+24V LED Array.
+12v ................................................................................... Main Board (CPU).
.12v
................................................................................... Main Board (CPU).
++5v ................................................................................... Main Board (CPU).
HV (+24V) .......................................................................... Thermal head.
1. Noise Filter Block
L701 , L702 ......................................................................... Line Filter
C702, C707 ........................................................................ Across the line capacitor.
C703, C705, C706, C708, C709 ........................................ Line-by-path capacitor.
2. AC DC converter Block (Primary)
D701 (Bridge Rectifier) ....................................................... Full wave rectificating diode.
c710 ................................................................................... Smoothing capacitor.
3. Switching circuit Block
Q701 (Power
MOS
FET) .................................................... Main power transistor.
T701 ................................................................................... Switching power transformer.
4. Switching control Block
IC701 ..................................................................................
pulse wide modulation (PWM).
Over current limitation (OCP).
Stabilize the output (+24V) and
protect against electric hazards.
5. AC DC Converter Block (Secondary)
D704 ................................................................................... Rectificating diode (3 pin type).
L703 ................................................................................... Smoothing choke coil.
C720 ................................................................................... Smoothing capacitor.
6. Comparator Block
Q704 ................................................................................... Comparative transistor.
ZD704 ................................................................................. Reference Voltage: 506V
VR701 ................................................................................ Variable resistor (adjust the+24V)
7. DC * DC Converter Block
VIN+24V) _VOUT(+5V,t12V)
lC702 .................................................................................. Step-down chopper control IC.
lc703 .................................! ................................................ 3 pin type voltage regulator (+12V).
lc704 .................................c................................................ 3 pin type voltage regulator (-12V).
D705 ................................................................................... Fly-wheel diode.
D706, D707 ........................................................................ Rectificating diode.
L704 ................................................................................... Smoothing choke coil (Triple output
........................................................................................... inductor).
C724, 725,726, 729 ...........................................................
Smoothing
capacitor.
8. Semiconductor Switch Block
Q702 (Power MOS FET) .................................................... Supply +24Vfor thermal head.
Q703 ................................................................................... ON/OFF controlled the signal
(HVON) from CPU.
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