Epson 2070 Service Manual - Page 65

POWER SUPPLY OPERATION, Power Supply Output Voltages and Applications - driver lq

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LQ-2070 Service Manual Operating Principles 2.2 POWER SUPPLY OPERATION The printer can be powered by either of two power supply boards: the C166 PSB (120 V) or C166 PSE (230 V) power supply. These boards are the same as the FX-2170. Additionally, the PSB and PSE boards function the same, except for a difference in primary circuitry. The power supply board outputs the DC current necessary to drive the printer control circuits and drive mechanism. Table 2-5 shows the input voltages and fuse ratings for these boards. Table 2-5. Power Supply Board Board C166 PSB C166 PSE Input Voltage 103.5 to 132 VAC 198 to 264 VAC Fuse F1 Rating 3.15 A / 125 V T2.0 AH / 250 V 2.2.1 Power Supply Overview The power supply board has two power outputs for use by the various control circuits and drive mechanisms. Table 2-6 lists the applications for the two DC output supply voltages. Table 2-6 Power Supply Output Voltages and Applications Output Voltage (DC) Applications +5 V Main Board Logic Circuit Sensors +35 V CR Motor PF Motor Figure 2-22 shows a block diagram of the power supply circuitry. Control Panel LEDs Printhead Driver Primary Circuit Secondary Circuit +5V Switching Regurator +5V Constant Voltage Control Circuit +5V Over current Protection Circuit +5V DC Full Wave Rectification Circuit Smoothing Circuit Filter Circuit AC input Switching Circuit Smoothing Circuit PhotoCoupler PhotoCoupler +35V Line Over Load Detector Circuit +35V Line Constant Voltage Control Circuit +35V Line Over Voltage Protection Circuit +5V Line Over Voltage Protection Circuit +35V Line Over Current Protection Circuit +35V DC CPU Port 20 Operation SW Figure 2- 22 Power Supply Circuit Block Diagram As shown in the figure above, when AC power enters the printer from an external power source, the filter circuit removes the noise. The AC voltage then undergoes full-wave rectification and is smoothed to produce direct voltage. The voltage is fed to the gate port for the switching FET (Q1: K2126 or K21230) through resistors R18 and R31, and then the switching circuit operates. The secondary smoothing circuit produces a stepped down +35 VDC voltage. The +5 VDC voltage is generated by feeding the +35 VDC voltage through the +5 VDC power supply circuit, where the +35 VDC is stepped down to a stable +5 VDC from the 35 VDC line. Rev.A 2-17

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2.2
POWER SUPPLY OPERATION
The printer can be powered by either of two power supply boards: the C166 PSB (120 V) or C166 PSE (230
V) power supply. These boards are the same as the FX-2170. Additionally, the PSB and PSE boards function
the same, except for a difference in primary circuitry. The power supply board outputs the DC current
necessary to drive the printer control circuits and drive mechanism. Table 2-5 shows the input voltages and
fuse ratings for these boards.
Table 2-5.
Power Supply Board
Board
Input Voltage
Fuse F1 Rating
C166 PSB
103.5 to 132 VAC
3.15 A / 125 V
C166 PSE
198 to 264 VAC
T2.0 AH / 250 V
2.2.1
Power Supply Overview
The power supply board has two power outputs for use by the various control circuits and drive mechanisms.
Table 2-6 lists the applications for the two DC output supply voltages.
Table 2-6
Power Supply Output Voltages and Applications
Output Voltage (DC)
Applications
+5 V
Main Board Logic Circuit
Sensors
Control Panel LEDs
+35 V
CR Motor
PF Motor
Printhead Driver
Figure 2-22 shows a block diagram of the power supply circuitry.
As shown in the figure above, when AC power enters the printer from an external power source, the filter
circuit removes the noise. The AC voltage then undergoes full-wave rectification and is smoothed to produce
direct voltage. The voltage is fed to the gate port for the switching FET (Q1: K2126 or K21230) through
resistors R18 and R31, and then the switching circuit operates. The secondary smoothing circuit produces a
stepped down +35 VDC voltage. The +5 VDC voltage is generated by feeding the +35 VDC voltage through
the +5 VDC power supply circuit, where the +35 VDC is stepped down to a stable +5 VDC from the 35 VDC
line.
Filter Circuit
Full Wave
Rectification
Circuit
Smoothing
Circuit
Switching
Circuit
AC input
Smoothing
Circuit
+5V Switching
Regurator
+5V Over current
Protection Circuit
+35V DC
+5V DC
Photo-
Coupler
Photo-
Coupler
+35V
Line
Over Voltage
Protection Circuit
+35V Line
Over Load
Detector Circuit
+35V Line
Over Current
Protection Circuit
Operation
SW
Primary Circuit
Secondary Circuit
CPU
Port 20
+35V Line
Constant Voltage
Control Circuit
+5V Line
Over Voltage
Protection Circuit
+5V Constant Voltage
Control Circuit
Figure 2- 22
Power Supply Circuit Block Diagram
LQ-2070 Service Manual
Operating Principles
Rev.A
2-17