Iiyama Vision Master Pro 451, Service Manual

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(3) HORIZONTAL SIZE and DISTORTION CONTROL circuits
The variable B voltage control pulse synchronized with the horizontal sync signal is output from pin 14 of
IC350. The control pulse makes the PRESSOR CHOPPER circuit consisted of L955, Q951 and D964 output
the variable B voltage of horizontal deflection output.
The horizontal size control voltage and distortion control parabolic wave output from pin 5 are input to pin
11 and then the output pulse of pin 14 controls the horizontal size and distortion as follows:
Q
H-size: The output duty of pin 14 is varied by the DC voltage input to pin 11.
R
Distortion: The parabolic wave (AC component) input to pin 11 is synthesized with the output pulse of
pin 14.
DC component
... H-size
AC component ... Distortion
IC350 pin 5 output
(0.5V/div)
IC350 pin 26 H-sync input
(5V/div)
IC350 pin 18 AFC input
(5V/div)
IC350 pin 17 HD-OUT output
(10V/div)
IC350 pin 14 Variable B
control pulse (0.5V/div)