Operating Principles
VDC line over-current protection circuit
VDC line drops to
VDC, the sensor circuit consisting ofR172 (R272)
and R173 (R273) turns on Q153 (Q253). Q154 is turned on, PC2 is turned on, and
then the input voltage is cut. At this time, the delay timing creation circuit (CR
circuit) consisting of Cl57 and R174 makes the delay timing. When the printer is
turned on, the delay timing creation circuit cannot start this protection circuit; if
it is operated during the printhead driver check, the power supply board cannot be
turned on. The CR circuit has approximately a one-second delay timing.
VDC power-down detection circuit
When the
VDC line drops (such as, when the printer has exceeded its duty
cycle and the printhead temperature is too high), the voltage
approaches
0 VDC.
voltage drops to 1.3 VDC, IC152 outputs a HIGH CLIMIT signal to
the base oftransistor Q187. IC152 monitors the two
VDC line creation
circuits.
VDC creation circuit
When the printer is turned on, the Cl 17 power supply board assembly creates
VDC to check the printhead drivers on the Cl 17 MAIN board assembly. After 140
ms, the Cl 17 MAIN board assembly sends the DRERR (driver error) or the VPC
VDC permission) signal to the Cl 17 power supply board assembly.
printhead drivers are normal, the VPC signal is HIGH, Q182 is turned on, and
1 is turned off. Therefore, six Zener diodes create the
VDC. During the
motor driver check, the VPC signal is LOW. When this signal is LOW, Q182 stays
off, the base of Q182 stays HIGH, and then two Zener diodes (ZD15 1 and
output
VDC.
EPSON
Service Manual
2-19
Summary of Contents for DFX-5000+
Page 1: ...EPSON Service Manual Epson America Inc TM DFX5K ...
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Page 212: ...Appendix Table A S CN7 C117 MAIN Board Assembly A 8 EPSON DFX 5000 Service Manual ...
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Page 220: ...Appendix Figure A 5 Exploded Diagram 2 A 16 EPSON DFX 5000 Service Manual ...
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Page 223: ...Appendix Figure A 7 C117 MAIN Board Circuit Diagram EPSON DFX 5000 Service Manual A 19 ...