8-14
2-3. VERTICAL DEFRECTION CIRCUIT
The vertical deflection circuit is constructed by following three blocks.
1) Sawtooth wave generating, vertical size and position control and linearity control circuits
2) Vertical filter circuit
3) Vertical output amplifier circuit
a. Sawtooth wave generating, vertical size and position control and linearity control circuits
The vertical sync signal from IC7A1 on VIDEO PWB is fed to IC501 pin 42 on OSC PWB. DSP in IC501
generates saw wave by calculations. The signal, after the AGC in this saw wave, is moved to vertical
deflection control signal. This vertical deflection control signal is output from IC501 pin 1. After IC501
receives vertical size data, vertical position data, vertical max. size data, vertical raster position data,
vertical linearity data and vertical linearity balance data from MPU, IC501 pin 1 outputs vertical saw wave
which is controlled by these correction items.
The vertical max. size control is standard adjustment item for vertical size. The vertical raster position
control is standard adjustment item for vertical position. These control items do not have the function of
tracking operation for distortion correction.
b. Vertical filter circuit
IC501 pin 1 output of vertical saw wave is converted 1.7V DC to 0V DC and amplified 14.5 times by
IC511.
The output signal of IC501 includes digital noise because it is generated by digital circuit. After this digital
noise is eliminated by filter circuit which are composed of IC421 and its peripheral circuit, the vertical saw
wave is sent to the vertical output amplifier circuit.
The vertical saw wave is input to IC421 pin 3. After this vertical saw wave is combined with output signal
at IC421 pin 7, this combined signal passes the low pass filter composed of R529 and C423. The low
pass filter eliminates the digital noise and the vertical saw wave output from IC421 pin 8. Q421, Q422
and Q423 are correction circuit for vertical linearity. These FET are controlled by IC532 based on vertical
frequency. Figure 2.12 shows IC532 output voltage.
R425
IC511
R421
R427
R424
R423
R422
IC421
IC421
R426
R428
R429
C423
C424~C426
C429
1
2
Vertical output
10bitDAC
1.7Vdc out
R50P
R50C
R50E
R50A
R50M
IC511
0Vdc
Approx.8Vp-p
1.7Vdc
Approx.0.55Vp-p
Q421 Q422 Q423
3
2
1
7
9
8
10
5
6
13
12
14
(
Fig. 2.11) vertical saw wave output and filter circuits