LG LST-5600A Service Manual page 29

(C2)
YES
Check RGB cable is connected
YES
Check PC resolution
YES
Check H:CN203(2)(Fig.10 top).
V : CN203(1) (FIG.10 middle), R:CN203(9),
G:CN203(5) ,B:CN204(4) (FIG,10 bottom)
YES
Check input selection is low : IC506(1)
YES
Check ADC output CLK: IC504(67),
H:IC504(66),V:IC504(64) : (FIG,11~13)
Digital data: IC504 pin 2~9,12~19,70~77 : (FIG.14)
YES
Is there any quantize noise ?
NO
End
When RGB is main
NG
NG
NG
NG
If the pin is high, check IC201(23)
If IC203(23) is high then try power off/on.
NG
YES
3-22
Connect RGB cable
Change resolution to 1024 x 768
Check cable or video card
Change IC504 component
Check IC400