Specifications
REV.-A
2.2 OPERATING PRINCIPLES OF POWER SUPPLY CIRCUITRY
The power supply circuitry of this printer is provided with
either
C076PSB board (120V) or C076PSE
board (220/240 V). Both boards operate in the same way although the elements in the primary circuit
are partly different.
The power supply unit supplies DC voltage which is used for controlling the printer of driving the printer
mechanism.
Table 2-4 shows the ratings of the power supply board.
Table 2-4. Ratings of Power Supply Board
Board Name
Input Voltage
(ACV)
Fuse (F I ) Rating
C076PSB
103.5-132
2.5 A/
125 V
C076PSE
198-264
1.25 A/ 250 V
2.2.1 Voltage Allocation
The DC voltage generated by the power supply circuitry is allocated to each circuit or mechanism
depending on their voltage level. The details are described in Table 2-5.
Table 2-5. Voltage Allocation
Voltage
Application
+35
VDC
Carriage motor drive
Paper feed motor drive
Top edge motor drive
Pump motor drive
Printhead drive voltage (VH) generation
+5
VDC
C076 MAIN board logic circuit
Sensors
Control panel LED
Top edge motor holding
2.2.2 Operating Principles of Power Supply Circuitry
Figure 2-37 shows the block diagram of the power supply circuitry.
The AC power supplied from the external source is first sent to the filter circuit, where higher harmonic
is cut. The AC voltage is then rectified and smoothed into the DC voltage. This DC voltage is sent to
the switching circuit and then to the smoothing circuit of the secondary circuitry, and thus dropped
to +35
VDC
voltage. This +35
VDC
voltage is fed back to the switching circuit by the + 35V line voltage
detection circuit and thus stabilized.
The +35VDC voltage is also sent to the
+5VDC
power supply circuit and thus dropped to stable +5
VDC
voltage.
This circuitry is provided with four types of protection circuits as described below.
1
) + 5
VDC
line over voltage/current protection circuit
When the current flowing on the + 5
VDC
line increases, the over current protection circuit cuts
the current. When the voltage of the +
5VDC line exceeds a certain value
(+
7V), the switching circuit
is turned off to stop the generation of +35
VDC
voltage. The over current protection circuit is
included in the over voltage protection circuit.
2-27