Service manual

2-16 Mechanism Configuration and Operating Principles Rev. B
Confidential
Principles of Operation
Power Supply Circuitry
The power supply circuit is compact, uses a switching method, and is attached to the main
circuit board. The following sections describe printer power supply circuitry. The following
table shows power supply voltages and their usages.
Filter circuit
The +24 V (24 to 30 V) DC power is input from CN1 through the filter circuit, which reduces
outside noise and keeps internally generated noise from flowing through the +24 V power line.
+24 VDC circuit
The +24 V power from the filter circuit is input to printer power and the +5 V regulator circuit.
Printer power and drawer drive power are the converted +24 ± 1 V that is regulated by series of
regulators (U2 to U4).
+5 VDC control circuit
The +5 V regulator circuit switches the +24 V power input and converts it to +5 V. The switching
regulator IC (U1) switches the +24 V input, smooths it via C1, and outputs +5 V. Power for the
RS-232 is generated by the internal charge-up circuit on the RS-232 interface driver.
Power supply voltage usage
Voltage Usage
+5 V Logic circuit Interface circuit board
Operation panel circuit Various detector circuits
+24 V Printer:
Carriage motor Paper feed motor
Print head Auto-cutter
Drawer kick-out drive
Figure 2-19 Power supply circuit diagram