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 U14_PIN3 is 5V?
Check if the voltage of
T1_PIN1 is 3.3V?
Y
Check if T1_PIN10
、
11
have I
2
C signals?
N
N
N
Y
Check the
power supply
of M 5V
Y
Check if T1_PIN2,3
have IF signals?
Check the circuit from
T1_PIN2,3 to
U18_PIN37,38 and
Y
N
Check the circuit
between
T1 PIN10 11 and
Change
U14
Change the
defective
N
N
of M_5V
have IF signals?
_
T1_PIN7,8 to
U1_PIN184,185
Check if the voltage of
Y
Change
T1_PIN10,11 and
U18_PIN45,46
components
Y
N
T1_PIN4&PIN9 is between 0 and 2.5V?
Check RF_AGC
circuit,such as R308
、
T1
ATV can't scan
any channel
DVB-T/T2/C can't scan
any channel
Check if U1 PIN217
~
Y
C67,R309 and C147
、
R333,R334,R335
、
C222.
Check RP2
Check if U6_PIN122
~
Change U1
Check if U1_PIN217
~
220 have TS signals?
Y
N
1,Check if 3.3V,1V power supply of U6 are normal?
2 Check if frequency of 27MHz crystal oscillator
Check the circuits of
power supply and
Y
N
N
and R296
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 U6 are
Change the
defective
defective
components
U6_PIN95,96,98,67
and U1 is normal
components of U6 are
normal?
defective
components
Y
Change U6
第 50 页,共 57 页
Summary of Contents for STV-22LED3
Page 1: ...SERVICE MANUAL STV 22LED3 STV 24LED3 第 1 页 共 57 页 ...
Page 30: ...9 Housing ASSEMBLY DRAWING 结构尺寸 第 30 页 共 57 页 ...
Page 31: ...系列 公司名称 东莞乐科电子有限公司 机种名称 拟制 日期 审核 尺寸 版本 批准 第 31 页 共 57 页 ...
Page 55: ...STV 22LED3 Line Diagram 第 55 页 共 57 页 ...