Vertical Compensation And Geometrical Compensation Of The Raster - NEC MultiSync V720 Service Manual

5.

Vertical compensation and geometrical compensation of the raster

LM1295:
1. Vertical scanning frequency : 50 to 100Hz.
2. DC control compensation amplitude
3. Temperature stability of the vertical amplitude : 1%.
4. Dynamic vertical deflection compensation corresponding to the secondary anode voltage drop.
5. Positive and negative compensation signals.
Block Diagram
Osc
Cap
20
4
Osc.
V Sync in
2
V Height
1
Gnd
6
V Dyn
Height
V
V Dyn
15
Focus
Cntl
H Trap
11
Cntl
E-W Pin
10
Cntl
H Para
12
Cntl
13
H Bow
Cntl
LM1295 Application
Negative
going V Sync
12V
R2
10K Ω
VR1
5K Ω
2f ALC
Cap Cap
19 18
Auto
Gain
Level
Adjus
-(V)²
V Dyn.
-(X)²
Focus
H
E-W
Trap
Pin
H
H
Para
Bow
R1 10K Ω
U1
21
22
LM1295
Rvert Rvert
1
Gnd V Drive
10uF
3
C1
4V Cap
100uF
5
C2
8V Cap V Drive
10uF
8
C3 OSD Cap
Vref Cap
21 Cap
4
V Sync in
ALC Cap
2
V Height
7
Vcc
V Dyn
R3
Focus Cntl
150K Ω
V Dyn
V Dyn
6
Height
Focus
S Amplitude Adj.
R5
R4
50K Ω
10K Ω
Rvert Rvert
21 22
24
Vertical
23
output
7
17
5
8
-
16
+
3
R R
-
9
3R
+
4V
-
14
R
+
R R
S Center Adj.
24
200K Ω
VR4
R9
10K Ω
23
0.1uF
20
C8
0.47uF
19
C7
4.7uF
18 C6
R6
17
Gnd
300K Ω
15
16
C4
C5
10uF
10uF
VR2
200K Ω
59
+ Vertical Drive
- Vertical Drive
Vcc (12V)
GND
8V Cap
V REF Cap
V Dyn Focus
4V Cap
H Dyn Width
H Dyn Cntl
TO V Deflection
Output Amp.
R8
10K Ω
R7
10K Ω
VR3
5K Ω