Service manual

Page 20 of 64
4-2-4 RGB or DVI mode defective
OK
OK
LED orange
LED red or no
response
NG
Yes, there are have OSD
D-SUB，HDTV
Mode mo dis
p
la
y
Check power switch is
in “POWER ON”
status, and check DC
POWER block
Disconnect the signal
cable, is the screen show
“Searching”
Connect signal cable again
1.D-SUB(or HDTV)mode:
Measure Y, Pb, Pr (or R,
G,B) input signal at U14.
2.Measure VSYNC and
HSYNC input signal at
U14.
Reference the circuit
diagram and check
scalar(U20) circuit: (eg.
RA1,RA11,RA12,RA13
voltage=3.3V?),and check
the waveform of SDA and
SCL right?
OK
Connect the signal
cable again, check
LED status.
Check the wire from
J34 or J36 is tight
enough? Check the
panel side too.
Check relevant circuit
whether have short or
open, and check the
signal cable whether
normal.
Open the “power”
(push power of key
board or RC), if the
LED still orange or no
response, check CPU
power and U52, U53.
NG
All voltage is normal?
L45
MST9883
Short SW2(RESET)
restart the system, and
check LED and screen
status.
Check the TTL and
DCLK output of
SCALER.
R12
R117
R120
R121
DEN
DCL
K
U14