DEC VT220 - Page 171

FLYBACK
TRANSFORMER
PRIMARY
ITl i
FROM
VIDEO
LOGiC
HORIN
HORiZONTAL
PROCESSOR
HORIZONTAL
DRIVER
HORIZONTAL
OUTPUT
HORIZONTAL
WINDINGS
(YOKE ASSYI
Figure 8-4 Horizontal Deflection Circuit BloCK Diagram
R209
820
C205
.1
100V
R210
lOC1/2W
R211
looB
C206
470
16V
C207
.068 'i'
lOCV I
C208...L
.027 .........
250V
TO
HORIZ
.. 4-+--------'----- DRIVER
R215 IR212
2 18K FROM
HORIZ
OUTPUT
10202
COLLECTORj
R206
1.2K
ZDI
3.6V
196
E201
MC1391P
R205
150K
R204
16.5K
1% 6 8
R203
5K
,
R202
18K
FROM
r---,-----r--r-----r---r~{Y- .. ---- +12V
FILTER
}-_..L-_-L __ ...L.. ..L- __ .L- ........ GND 8
C200
3OCP500,
GND
HOP R200
FROM
lr, 1.8K 3
VIDEO
121---,-"""'....,.---+---1
LOGiC J2
P",
OUTPUT TO PUlSEWIDTH MODULATOR FROM
E201,
PiN 1, IS NOT SHOWN IN SCHEMATICS.
THIS OUTPUT SYNCHRONIZES
PUlSEWIDTH
MODULATOR OPERATION TO HORIZONTAL
RETRACE PERIODS
Figure 8-5 Horizontal Processor Circuit Diagram
8-5