Auto Adjust Circuit; Block Diagram - NEC MultiSync FP1370 Service Manual

12. AUTO ADJUST CIRCUIT

By detecting video signal, AutoAdjust function adjusts size and position. MPU has several standards of
frequency, active ratio and so on. MPU compares measurement data and with their standards, and calculates
adaptive size and position data and sets them.
IC8M1 is video detecting IC. It measures following data.
H.trace.time, H.disp.time, H.front.porch, H.back.porch
V.total.time, V.disp.time, V.front.porch, V, back.porch
That means AutoAdjust function can't work correctly in the cases as follows.
a. No signal (ex. All black)
b. Too narrow active ratio (ex. 1/3 window)
c. Animation (ex. movie, game)
d. Too dark
If Animation, sometimes AutoAdjust function can detect video signal and sometimes can't. As a result
AutoAdjust function can't work stably.
A blinking picture is worst case.
Video
Pre-Amp
Horizontal
Deflection
Circuit
AFC_TTL
Auto Adjust
Circuit
Video Signal
(IC8M1 QFP32)
V_PUMP
Vertical
Deflection
Circuit
(Fig.12.1) Auto Adjust Circuit Block Diagram
8-63
MPU
(IC801)