Philips L04E Service Manual page 17

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5.8.6
Tuner and IF
No Picture
1. Check that the Option settings are correct.
2. If correct, check that supply voltages are there.
3. If supply voltages are present, check whether picture is
present in AV.
4. If picture is present in AV, check with the scope the Tuner
IF output signal by manual storage to a known channel.
5. If IF output is present, Tuner is working fine. If no IF output,
I2C data lines may be open, check continuity of I2C lines.
If I2C lines are ok, Tuner may be defect, replaced Tuner.
6. If Tuner IF is present and yet still no picture in RF mode, go
to Video Processing troubleshooting section.
No Picture, No Sound
No Picture,
No Sound,
Raster Ok
Check AGC
Voltage, pin 1
of tuner
Yes
AGC voltage
changes with
different signal
strength
No
Check AGC
circuit section
Figure 5-13 Fault finding tree "No picture, no sound"
Service Modes, Error Codes, and Fault Finding
Check tuning
supply voltage,
pin 9 of tuner
Check
>30V & <35V
V
Supply
No
T
Section
Check supply
voltage, pin 7 of
tuner
Check Power
5V
No
Supply
Yes
Check Tuner
pin 4 & 5
I 2 C Bus
Check other
Ok
No
functional area
Yes
Replace Tuner
E_14480_062.eps
170204
L04E AB
Picture Ok, No Sound
Picture Ok,
No Sound
Check IF output of
tuner, pin 11
Refer to fig.
CVBS
No
"Power Supply:
present?
Set not working"
Yes
Check SAW filter output
(pin 4&5)
EU/AP/CH (QSS)- 1001
NA/LA/AP INT - 1002
Replace SAW
Output Ok?
No
Yes
Check other
functional area
Figure 5-14 Fault finding tree "Picture ok, no sound"
Unable To Perform Tuning
Unable to
perform tuning
Enter SDM
Enter SDM and change
check optionbyte 1
Incorrect
Correct
Check if tuner
Supply Voltage
5V
No
pin 7
Yes
Check Tuner
Supply Voltage
Yes
Check I 2 C at pin
4 & 5 and tuner
Not Ok
Ok
Check other
functional area
Figure 5-15 Fault finding tree "Unable to perform tuning"
5.
EN 17
filter
E_14480_063.eps
170204
to the appropriate byte
Check I 2 C
Check Power
Replace
circuit
Supply
Tuner
No
33V
Not Ok
Not Ok
I 2 C
Tuner
Not Ok
E_14480_064.eps
170204

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