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REV.-A
Figure 2-18 shows a block diagram of the power supply circuit.
External noise on the AC input line is first attenuated by the input filter circuit. Then the input AC is -““
rectified by the full-wave rectifier circuit and smoothed by the smoothing circuit.
Surge current that flows when the printer power is first turned on is suppressed by the
suppression circuit.
The voltage output from the smoothing circuit is converted to various voltages for the control circuits
(+5 V and
12
and drive circuits
V).
When main switching circuit 1 is activated, voltage is induced in the secondary side of transformer
by electromagnetic coupling with the
side. The voltage is rectified and smoothed separately
into + 5 V and
12 V.
After being rectified and smoothed, the + 5 V output is fed back to main switching circuit 1 by the current
limiting and voltage regulator circuits via the photo coupler, and stabilized.
When the power supply for the control circuits starts operating normally, voltage is induced in the
secondary side of transformer T2. Upon receiving this voltage, main switching circuit 2 turns on, and
voltage is induced in the secondary side of transformer T3. After being rectified and smoothed, the
+35 V output is fed back to main switching circuit 2 by the current limiting, voltage regulator, and .
over voltage protection circuits, and is stabilized.
Power SW.
INPUT FILTER
FULL-WAVE
RECTIFIER
SURGE-SUPPRESSION
SMOOTHING
CIRCUIT
CIRCUIT
CIRCUIT
CIRCUIT
-
PRIMARY SIDE
SECONDARY SIDE
I
1
MAIN SWITCHING
m
RECTIFIER AND
CIRCUIT 1
SMOOTHING
CIRCUIT
r
RECTIFIER AND
CURRENT LIMITING
SMOOTHING
AND VOLTAGE
—
CIRCUIT
—
CIRCUITS
PRIMARY SIDE T2 SECONDARY SIDE
-
THE
ANALOG
AND LOGIC
+5 CIRCUITS
PRIMARY SIDE T3 SECONDARY SIDE
RECTIFIER AND
CURRENT LIMITING
TO THE
MAIN SWITCHING
OVER VOLTAGE
SMOOTHING
AND VOLTAGE
MECHANISM
CIRCUIT 2
PROTECTION
CIRCUIT
DRIVE
- REGULATOR CIRCUITS
CIRCUIT
CIRCUITS
Figure 2-18.
Board Block Diagram
2-26
Summary of Contents for LQ-2550
Page 1: ...L Q 2 5 5 0 TECHNICAL MANUAL EPSON ...
Page 240: ...REV A P r cl Figure 6 3 LQ 2550 Lubrication and Adhesive Application Points Diagram 2 6 3 ...
Page 241: ...REV A 7 i_ Figure 6 4 LQ 2550 Lubrication and Adhesive Application Points Diagram 3 6 4 ...
Page 252: ...REV A I 1 I 7 v m o m x b Figure A 6 PPD781OHG Block Diagram A 7 ...
Page 297: ...REV A 1 L I Irl N I i t 1 I I x Figure A 50 ROPSE Board Circuit Diagram A 52 ...