Service manual

Page 23 of 64
4-2-7 直流电源电路
4-2-8 Scaler and LVDS block
Check the input and output
signal at U20.
OK
Check the input and output
signal at U30.
Replace U30
Check relevant circuit whether
have short/open .
OK
NG
NG
NG
OK
Check the wire from J40/J41
or J43/J44 is tight enough?
Measure the DC input voltage:
L49 --Æ 5 V
L48 --Æ 5 V
L61 --Æ 6 V (SAMSUNG PANEL)
L60 --Æ 12 V (SAMSUNG PANEL)
L50 --Æ 12 V (SAMSUNG PANEL)
L44 --Æ 3.3 V
L43 --Æ 9 V
OK
Check relevant circuit whether
have short .
Is there any shortage or cold
solder?
Measure Pin2 at U23,U24,U25:
U23--Æ PIN2 = 1.5V
U24--Æ PIN2 = 3.3V
U25--Æ PIN2 = 2.5V
Measure Pin2 at U5,U10,U11,U41:
U5 --Æ PIN2 = 2.5V
U10--Æ PIN2 = 3.3V
U11--Æ PIN2 = 3.3V
U41--Æ PIN2 = 5V
Measure voltage at L*：
L4 --Æ PIN = 5V
L24 --Æ PIN = 5V
L22,L23 --Æ PIN = 3.3V
L8，L9，L10 --Æ PIN = 2.5V
L31，L32 --Æ PIN = 3.3V
L7 --Æ PIN = 3.3V
L45 --Æ PIN = 5V