EPSON Stylus Scan 2500 Revision A
Operating Principles Electrical Circuit Operating Principles 56Figure 2-22. B101 PSB/PSE Board Block Diagram
+24V line over
voltage limitation
ZD91
Fuse Filter circuit
Full wave
rectifier circuit
F1 L1, R1,
C1-4 DB1
Smoothing
circuit Main
switch-
Q1
C11
Q2,Q3,Q
31,IC1
Transformer (T1)
Smoothing
circuit Power drop
delay circuit
+12V
regulator
+12V line over
voltage limitation
D51
C51,C52
ZD51,ZD81-86
+12V
ZD42
+42V line constant
control
IC53
+42VDC line over
voltage limitation
+5V line over
voltage limitation
Photo coupler
Feedback
circuit
PC1
C57,Q82,
Q84
Power signal
from MAIN
board/power
switch
+5V regulator
+5V
+42V
IC51
ZD52,87
ZD53
AC input
+3.3V regulator
+3.3V
PRIMARY SIDE
SECONDARY SIDE
D89D88
+24V
regulator
IC52
+24V
+24V line over
voltage limitation
ZD91
IC151