Operating Principles
Rev. A
2-17
Figure 2-18 illustrates the electrical circuit diagram.
+5 VDC line over voltage protection circuit
The output voltage level of the 5 V line is monitored by a Zener diode (ZD53). If the voltage level
exceeds 9 V, the status is fed back to the primary switching circuit through the transistor (Q82) and
photocoupler (PC1) to cut the +42 V line to the regulator (OC51).
+5 VDC line constant voltage control circuit
Voltage at +5 VDC line is controlled by the regulator IC (IC51). When the abnormal voltage at +5
VDC line is detected, the status is input to the internal comparator of the regulator to control the
voltage.
+42 VDC line over voltage protection circuit
The output level of the +42 VDC line is monitored by the 2 Zener diodes ZD52 and ZD87. When the
output level of the +42 VDC line e48 V, the switching FET operation on the primary side is
stopped via the thyristor (CY52), transistor (Q81) and photocoupler (PC21).
+42 VDC line constant voltage control circuit
Voltage at the +42 VDC line is monitored by the Zener diodes (ZD51, ZD81
ZD86). This circuit feeds
back the output voltage level status through photocoupler (PC1) to the primary switching circuit to
control the on/off time of the switching FET for constant output voltage.
+42 VDC line overcurrent protection circuit
The output current is monitored by the transistors Q81 and Q82. When the output current is
abnormally low, the status is assumed to be a short circuit and the information is fed back to the
primary circuit to stop the switching FET operation
Full Wave
Rectifier
Circuit
Filter
Fuse
AC Input
Smoothing
Circuit
Switching
Circuit
(Q1)
Half Wave
Rectifier
Circuit
Chopping
Regulator
(IC51)
+42 V
Line Detector
Circuit
(ZD51, 81 to 86)
+42 V
Line Over Current
Protection Circuit
(Q81, Q82)
+5 V
Over Voltage
Protection Circuit
(ZD53, Q82)
Power Off Delay Circuit
(ZD88, C84, Q84)
Primary Circuit
Secondary Circuit
+42 V
+5 V
Power Off Signal
Photo-coupler
PC1
+42 V
Line Over Voltage
Protection Circuit
(ZD52, ZD53, ZD87, Q82, Q83)
Figure 2-18. Power Supply Circuit Diagram
Summary of Contents for 1520 - Stylus Color Inkjet Printer
Page 138: ...Maintenance Rev A 6 5 8 9 10 10 10 10 10 10 10 10 Figure 6 2 Lubrication Points 2 ...
Page 146: ...Appendix Rev A A 7 A 2 Circuit Diagrams Figure A A 2 C211 MAIN B Board Circuit Diagram 1 2 ...
Page 147: ...EPSON Stylus COLOR 1520 Rev A A 8 ...
Page 148: ...Appendix Rev A A 9 Figure A A 3 C211 MAIN B Board Circuit Diagram 2 2 ...
Page 149: ...EPSON Stylus COLOR 1520 Rev A A 10 ...
Page 152: ...Appendix Rev A A 13 A 3 Component Layout Figure A A 6 C211 MAIN B Board Component Layout ...
Page 153: ...EPSON Stylus COLOR 1520 Rev A A 14 Figure A A 7 C172 PSB Board Component Layout ...
Page 154: ...Appendix Rev A A 15 Figure A A 8 C172 PSE Board Component Layout ...
Page 156: ...Appendix Rev A A 17 Figure A A 10 Stylus COLOR 1520 Exploded Diagram 2 ...
Page 157: ...EPSON Stylus COLOR 1520 Rev A A 18 Figure A A 11 Stylus Color 1520 Exploded Diagram 3 ...
Page 165: ...EPSON SEIKO EPSON CORPORATION ...
