Operating Principles
The
VDC regulator circuit includes the following:
VDC line over-voltage protection circuit
VDC line exceeds
VDC, the current flows to ZD153. Then
is
turned on, the photo-coupler (PC2) is turned on, and the voltage
primary
side is cut off. This circuit is a common circuit with the DRERR signal feedback
circuit on the Cl 17 MAIN board assembly.
VDC line over-voltage control/over-current control circuit
IC15 1 (TL494) includes this control circuit. IC151 contains two internal
comparators. One comparator is used for over-voltage control. Pin 16
monitors the
VDC line.
voltage exceeds
V (pin
internal
comparator 1 outputs a HIGH signal. The other comparator controls the
V line
over-current. Pin 1
monitors the current
V line.
current
exceeds the set value (pin
the voltage becomes HIGH and comparator 2 outputs
a HIGH signal.
Both the comparator 1 signal and comparator 2 signal are tied by the wired OR. If
the output signal is HIGH from either comparator, the output signal is HIGH.
This switching procedure monitors the Cl and C2 ports. These switching
waveforms are controlled by PWM (Pulse Width Modulation), which changes the
level of the inverse terminal of comparator 1 and comparator 2.
Printhead driver detection circuit
This circuit prevents printhead damage when a printhead driver is damaged.
When the printer is turned on, the Cl 17 MAIN board assembly tells the Cl 17
power supply board assembly whether the printhead drivers are normal.
If a printhead driver is damaged, the Cl 17 MAIN board assembly sends the
DRERR signal to the Cl 17 power supply board assembly. When the Cl 17 power
supply board assembly receives this signal, it stops creating
VDC and
VDC.
printhead drivers are normal, the Cl 17 MAIN board assembly sends
the VPC signal to the Cl 17 power supply board assembly. When the Cl 17 power
supply board assembly receives this signal, it creates
VDC.
VDC Line Regulator Circuit
When the printer is turned on and the Cl 17 MAIN board assembly sends the VPC
signal, the
VDC line rises from
V to
V. The
VDC line circuit uses
a ringing choke convertor (RCC) AC input switching power circuit. This system
uses few parts and a small transformer, and is often used when a small power
supply is required.
EPSON DFX-5000+ Service Manual
2-17
Summary of Contents for DFX-5000+
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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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