ViewSonic VA550 Service Manual - Page 42

Service, Manual, TROUBLE, SHOOTING

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Service Manual VA55O TROUBLE SHOOTING VIDEO DOES NOT APPEAR Start Check the LED is lighted ? Power Saving 1 N Check if the power is OK L 1 Check the video cable Y and check if the Hsync or V-sync is over specifications I L Is contrast and brightnes too small Adiust contrast and brightness controls Backlight is turned on ? Check W05 (VDD, VEE, and Con.) Check the video amplifier (IC31) output R,G,B is normal Check IC31 clamping signal (pin19) input signal (pin2, 6, 11) and Vcc ViewSonic Corporation heck the A/ convertor (IC08) is OK? Check the PLLO (IC09) is OK? Check the Vcc input video level (pin85,88,91) and reference voltage (pin86,89,92) of IC08 Check IC09 I (pin6), H-sync (pin17), I CKL and pin 21,20 (CLK+, CLK-) Check the PLL1 (IC03) is OK ? Check IC03 (pin4, 5, 12) Check W07 is OK? Check the VLCD, ► GND, H-sync, V-sync, DCLK and DE-0 J Check ICO2 Vcc and Hsync-0, Vsync-0, DCLK-out, DE-out • End Page 40 CONFIDENTIAL- DO NOT COPY

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Service
Manual
VA55O
ViewSonic
Corporation
TROUBLE
SHOOTING
VIDEO
DOES
NOT
APPEAR
Start
Check
the
LED
is
lighted
?
Power
Saving
Is
contrast
and
brightnes
too
small
Backlight
is
turned
on
?
Check
the
video
amplifier
(IC31)
output
R,G,B
is
normal
N
Check
if
the
power
is
OK
L
1
1
Check
the
video
cable
Y
and
check
if
the
H
-
sync
or
V
-sync
is
over
specifications
I
L
Adiust
contrast
and
brightness
controls
Check
W05
(VDD,
VEE,
and
Con.)
Check
IC31
clamping
signal
(pin19)
input
signal
(pin2,
6,
11)
and
Vcc
heck
the
A/
convertor
(IC08)
is
OK?
Check
the
PLLO
(IC09)
is
OK?
Check
the
PLL1
(IC03)
is
OK
?
Check
W07
is
OK?
Check
ICO2
Vcc
and
Hsync-0,
Vsync-0,
DCLK-out,
DE
-out
•
End
Check
the
Vcc
input
video
level
(pin85,88,91)
and
reference
voltage
(pin86,89,92)
of
IC08
Check
IC09
I
(pin6),
H
-sync
(pin17),
CKL
and
pin
21,20
I
(CLK+,
CLK-)
Check
IC03
(pin4,
5,
12)
Check
the
VLCD,
►
GND,
H
-sync,
V
-sync,
DCLK
and
DE
-0
J
Page
40
CONFIDENTIAL-
DO
NOT
COPY