Chapter 2 Operating Principles
Rev. A
2-14
2.2.2.2 EEPROM Control Circuit
EEPROM(IC9) uses three lines serial in/output 1kbit EEPROM and records default setting values and
destination parameter. Control signals of EEPROM; CS,CK,DO, DI are attached in the CPU port P70
∼
73
and, are controlled. When the power off is detected, the CPU writes the necessary data to the EEPROM
before the +5V line drops out of the normal range. The other CPU access is done during power supply,
but the access for safety is not done when the CPU is in the reset state.
2.2.2.3 System Reset Circuit
The reset IC(IC12) of this printer sends reset signal to the CPU and gate array until +5V line for control
stabilizes after the power is turned on, and prevents the printer from going to mis-operation.
EEPROM
(IC9)
Power-off
CS
CK
DI
DO
CPU
(IC11)
INTO
P70
P71
P72
P73
Figure 2-10. EEPROM Circuit
ResetIC
(IC12)
+5V
/RESET
VOUT
/RESET
MRES
P26
Gate Array
(IC10)
CPU
(IC11)
Figure 2-11. Reset Circuit
Summary of Contents for LQ 670 - B/W Dot-matrix Printer
Page 1: ...EPSON IMPACT DOT MATRIX PRINTER EPSON LQ 670 SERVICE MANUAL SEIKO EPSON CORPORATION 4007875 ...
Page 5: ...v REVISION SHEET Revision Issued Data Contents Rev A May 28 1997 First issue ...
Page 114: ...Chapter 6 Maintenance 6 1 Preventive Maintenance 6 1 ...
Page 116: ...LQ 670 Service Manual Rev A 6 2 Figure 6 1 Lubrication Points ...
Page 122: ...LQ 670 Service Manual Rev A A 5 A 2 Circuit Diagram Figure A 2 C214Main Board Circuit Diagram ...
Page 123: ...Appendix Rev A A 6 Heat Sink Q1 D51 Figure A 3 C214PSB Board Circuit Diagram ...
Page 124: ...LQ 670 Service Manual Rev A A 7 Heat Sink Q1 D51 Figure A 4 C214PSE Board Circuit Diagram ...
Page 125: ...Appendix Rev A A 8 A 3 Component Layout Figure A 5 C214 Main Board Component Layout ...
Page 127: ...Appendix Rev A A 10 A 4 Exploded Diagram Figure A 8 Exploded Diagram ...
Page 128: ...LQ 670 Service Manual Rev A A 11 Figure A 9 Exploded Diagram ...
Page 129: ...Appendix Rev A A 12 Figure A 10 Exploded Diagram ...
Page 135: ...EPSON SEIKO EPSON CORPORATION ...
