Epson C117001-N Service Manual - Page 53

Line Regulator Circuit - dfx + drivers

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Operating Principles DFX-5000+ Service Manual 2.2.2 +5 VDC Line Regulator Circuit The +5 VDC line regulator circuit uses a ringing choke coil (RCC) system DC/DC converter. IC151 (TL494) A C2 cl 1 +11 +12 +35VIX b +3CV,, UI'L.,., )-P PRIMERY CIRCUIT - Zk ZD153 HZS7B-2 Figure 2-15. +5 VDC Line Regulator Circuit The rectified and smoothed DC voltage turns on the +5 VDC line first. RIM is a starting resistor. When the +35 VDC line becomes +13 V, switching regulator IC TL494 (IC151) creates a +5 V line. The power supply board uses a 2-step rise method. When the printer is turned on, the +35 VDC line outputs +13 VDC for 140 ms. The first rising voltage (+13 VDC) is used to check the printhead drivers on the C117 MAIN board assembly. If a printhead driver is damaged, the control board outputs the error signal (HIGH DRERR signal) to the power supply board. When the power supply board receives this signal, the photo-coupler is turned on and it cuts off the voltage of the primary side. This prevents printhead damage when a printhead driver is damaged. If the printhead drivers are normal, the control board outputs the VPC signal to the power supply board. When the power supply board receives this signal, the line rises to +35 VDC after 140 ms. me +5 VDC regulator circuit includes the following: D +5 VDC line over-voltage protection circuit If the +5 VDC line exceeds +7 VDC, the current flows to ZD153. Then Q155 is turned on, the phot~coupler (PC2) is turned on, and the voltage of the primary side is cut off. This circuit is a common circuit with the DRERR signal feedback circuit on the C117 MAIN board assembly. D +5 VDC line over-voltage control/over-current control circuit IC151 (TL494) includes this control circuit. IC151 contains two internal comparators. One comparator is used for over-voltage control. Pin 16 (+12) monitors the +5 VDC line. If this voltage exceeds +5 V (pin 15), internal comparator 1 outputs a HIGH signal. The other comparator controls the +5 V Iine over-current. Pin 1 (+11) monitors the current of the +5 V line. If the current exceeds the set value (pin 2), 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. Cl Printhead driver detection circuit This circuit prevents printhead damage when a printhead driver is damaged. When the printer is turned on, the C117 MAIN board assembly tells the C117 power supply board assembly whether the printhead drivers are normal. If a printhead driver is damaged, the C117 MAIN board assembly sends the DRERR signal to the C117 power supply board assembly. When the C117 power supply board assembly receives this signal, it stops creating +35 VDC and +5 VDC. If the printhead drivers are normal, the C117 MAIN board assembIy sends the VPC signal to the C117 power supply board assembly. When the C117 power supply board assembly receives this signal, it creates +35 VDC. 2-14 Rev. A

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Operating Principles
DFX-5000+
Service Manual
2.2.2 +5
VDC
Line Regulator Circuit
The
+5
VDC
line regulator circuit uses a ringing choke coil
(RCC)
system DC/DC converter.
+35VIX
-
b
C,,
I’.,.
A
IC151
C2
cl
(TL494)
1
+11
+12
-
+3VUL,
)-P
Zk
ZD153
HZS7B-2
PRIMERY
CIRCUIT
Figure 2-15. +5
VDC
Line Regulator Circuit
The rectified and smoothed DC voltage turns on the +5
VDC
line first.
RIM
is a starting resistor.
When the +35
VDC
line becomes +13 V, switching regulator
IC
TL494
(IC151)
creates a +5 V line.
The power supply board uses a 2-step rise method. When the printer is turned on, the +35
VDC
line outputs
+13
VDC
for 140
ms.
The first rising voltage
(+13
VDC)
is used to check the
printhead
drivers on the
C117
MAIN board assembly.
If
a
printhead
driver is damaged, the control board outputs the error signal (HIGH
DRERR
signal)
to the power supply board. When the power supply board receives this signal, the photo-coupler is
turned on and it cuts off the voltage of the primary side. This prevents
printhead
damage when a
printhead
driver is damaged. If the
printhead
drivers are normal, the control board outputs the
VPC
signal to the power supply board. When the power supply board receives this signal, the line
rises to +35
VDC
after 140
ms.
me
+5
VDC
regulator circuit includes the following:
D
+5
VDC
line over-voltage protection circuit
If the +5
VDC
line exceeds +7
VDC,
the current flows to
ZD153.
Then Q155 is turned on, the
phot~coupler
(PC2)
is turned on, and the voltage of the primary side is cut off. This circuit is a
common circuit with the
DRERR
signal feedback circuit on the
C117
MAIN board assembly.
D
+5
VDC
line over-voltage control/over-current control circuit
IC151
(TL494)
includes this control circuit.
IC151
contains two internal comparators. One
comparator is used for over-voltage control.
Pin
16
(+12)
monitors the +5
VDC
line. If this voltage
exceeds +5 V (pin 15), internal comparator 1 outputs a HIGH signal. The other comparator controls
the
+5
V
Iine
over-current. Pin 1
(+11)
monitors the current of the
+5
V line. If the current exceeds
the set value (pin 2), 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.
Cl
Printhead
driver detection circuit
This circuit prevents
printhead
damage when a
printhead
driver is damaged. When the printer is
turned on, the
C117
MAIN board assembly tells the
C117
power supply board assembly whether
the
printhead
drivers are normal.
If a
printhead
driver is damaged, the
C117
MAIN board assembly sends the
DRERR
signal to the
C117
power supply board assembly. When the
C117
power supply board assembly receives this
signal, it stops creating +35
VDC
and +5
VDC.
If the
printhead
drivers are normal, the
C117
MAIN
board
assembIy
sends the
VPC
signal to the
C117
power supply board assembly. When the
C117
power supply board assembly receives this signal, it creates +35
VDC.
2-14
Rev.
A