Shivaki STV-26ALED3, Service Manual

Page: 60 / 80

1.Check if the external RF input signal is normal.
6. Function Trouble 6. Function Troubleshooting
（ （
ATV/DVB ATV/DVB--T/T2/C T/T2/C
） ）
ATV/DVB-T/DVB-C can't scan any channel
p g
2.Check if the country, region and standard are set correctly.
Check if the voltage
of U7_PIN3 is 5V?
Check if the voltage of
T1_PIN2 is 2.5V?
Y
Check if T1_PIN5 、 6
have I 2 C signals?
N N
N
Y
Check the
power supply
of M 5V
Y
Check if T1_PIN10,11
have IF signals?
Check the circuit from
T1_PIN10,11 to
U14 PIN49 50 and
Y
N
Check the circuit
between
T1 PIN5 6 and
Change U7
Change the
defective
N
N
of M_5V
have IF signals? U14_PIN49,50 and
U1_PIN184,185
Check if the voltage of
Y
Change
T1_PIN5,6 and
U14_PIN57,58
components
Y
N
T1_PIN7&PIN10 is between 0 and 2.5V?
Check RF_AGC
circuit,such as R348 、
T1
ATV can't scan
any channel
DVB-T/T2/C can't scan
any channel
Check if U1 PIN217
～
Y circuit,such as R348 、
C259,R350 and
R351
、
C260
、
R352.
Check RP14
Check if
U18 PIN122
～
125
Change U1
Check if U1_PIN217
～
220 have TS signals?
Y
N
1,Check if 3.3V,1V power supply of U18 are
normal?
Check the circuits of
power supply and
Y
N N
and R335
U18_PIN122 125
have TS signals?
N
2, Check if frequency of 27MHz crystal oscillator
is normal?
Change the
defective
power supply and
crystal oscillator
Check if the circuit
between
Y
Y
N
Check if surrounding
components of U18 are
Change the
defective
defective
components
U18_PIN95,96,98,67
and U1 is normal
components of U18 are
normal?
defective
components
Y
Change U18
第 60 页，共 80 页