Epson LX-810 Technical Manual

REV.-A
2.2.1.4 +5V DC Power Supply Circuit
The
+5VDC is generated by the switching and step-down action that Q6 applies to the 24VDC supplied
from the
24V power circuit.
Immediately following power up,
VI of SR 1 will be LOW, so that Q6 will be ON. Therefore, + 24V will
be
supplie, via Q6, to the chopper circuit (D2, L2) and the smoothing circuit (C7). When the charge in
C7 reaches 5V, however, SR 1 brings VI into a high-impedance condition, and Q6 goes OFF. Thereafter,
based on this 5V charge,
Q6 will switch ON when the voltage drops, and switch off when the voltage
rises to a certain level. This intermittent action will generate a stable + 5V voltage.
The chopper circuit provided at the output stage acts, just as with the
24V voltage, to stabilize the
current.
R31 serves to control the 5V output
at a slightly higher (about 5 mV) level, so as to prevent voltage
drop to due switching delay.
*
+24V
Q6
B1 151
R18 ::
22<“
R19
82
C26~
470p
film
1
SR1
78L05A
+~’1
R37
2K
1
C27
-
-0.1 P
L2
LP201-2R550
D2 R16
ERB81 19.f[
-004
B2
Z13F503
-III 1 TA
C7
4701J
10V
~ +5V
+
7
—
Figure 2-2’1. +5V DC Power Supply Circwit
2-19

Epson LX-810 Specifications

General

Brand	Epson
Model	LX-810
Category	Printer
Language	English