Vdc Voltage Control Circuit - Epson LQ-510 Technical Manual

REV.-A

2.2.5 +24 VDC VOLTAGE CONTROL CIRCUIT

Figure 2-22 shows the + 24 VDC voltage control circuit. To maintain the correct voltage on the + 24 V line,
the main switching transistor goes off if the voltage exceeds 24 V. If excess voltage occurs, reverse current
flows through Zener diode ZD20, PC1 is activated, and the condition of the switching circuit is as shown
in Figure 2-23.
NOTE: Items in parentheses refer to the 220/240 V version.
LQ-510
D4
C10
0.01
R8 ON
Figure 2-22. +24 VDC Voltage Control Circuit
r
PRINCIPLES OF OPERATION
+24V DC
GND
2-19