Welch Allyn Atlas Service Manual page 99

Blanking Time: 1.2mSec
Horizontal: Scan Rate:
Reset Time:
Blanking Time: 5.7uSec
5.2 Vertical Amplifier:
5.2.1 Ramp Generator:
Vertical Sync
750uSec
16.7mSec
1
Vsync
R52
1.96K
A ramp generator is built from the integrator (U1A, C1, and R3). The slope of the integrator is: V =
(I*T)/C. The integrator is designed so that it ramps up 6.97V in 750uS and ramps down 3.95V in 15.9mS.
Diode D1 clips the output voltage at about 5.0V (U1-pin3 + Vdiode). Then the ramp resets at 5.0V each
cycle, and integrates down 3.95V.
+12V
C4
.047uF R12
562
8
R13
3 169
Ramp +
1
2
-
U2A R14
MC34072 562
4
C2
100pf MPSW51A
u2.2
R4
10K
R5
42.2K
u1.6
4
-
6
u1.7 7
+
5 u1.5
U1B
TLC272
8
R8
41.2K
+12V
vcadj
R9
vcadj+
+5V
1.47K R10 1K
Appendix A
31.5Khz
5uSec
Ramp Generator
R1
1K
U1.3
+5V
R2
7.50K
R3
U4A
23.7K
2 U4.2
74HCT04
R43
5.11K
d6.c 2 1
D6
1N4148
Vertical Amplifier
3
q1.b 2 Q1
1 MPSW01A
R15 38.3
q1.e
1
q2.b 2 vadj
3
Q2 R16 10 R17
Size Adjust
R6
41.2K
R7
41.2K
Zero Adjust
R11
vcadj-
1.96K
+12V
C3
.047uF
3
+
1
Ramp
2
-
U1A
TLC272
C1
.1uF
U1.2
2 1
D1
1N4148
+12V
C5
+
22uF
3
Q3 2 q3.b
MPSW01A 1
R18
562
1
2 q4.b
3
10 Q4
MPSW51A
L
Vertical Yoke
10/14/99
Vertical
Sync
3.95Vpp
750uSec
16.7mSec
+12V
R19
562
+5V
8
R20
169 5
+
7
6
-
R21 U2B
562 MC34072
4
u2.7 u2.6
R23
10K
5.0V
R22
10K