Philips L04A AB, Руководство по обслуживанию, Страница: 24 / 90

Service Modes, Error Codes and Fault Finding EN 24 L04A AB 5.
5.8.6 Controller
Below are some guidelines for troubleshooting of the Micro
Controller function. Normally Micro Controller should be
checked when there is a problem of startup.
1.
Check that both +3.3 V_dc and +1.8 V_dc are present.
2. Check that crystal oscillator is working.
3. Check that Power Good signal is at “high” logic, normal
operation.
4. Check that HERCULES is not in standby mode. Pin 15 of
HERCULES should be 0 V_dc.
5. Make sure H-drive pulse is there. This can be checked at
resistor R3239. If H-drive does not exist, remove resistor
R3239 to check if there is loading.
Note: When the set shuts down after a few second after power
“on”, the main cause is that Vg2 not aligned properly, try
adjusting Vg2 during the few seconds of power “on”.
5.8.7 Video Processing
No Picture
When “no picture in RF”, first check if the microprocessor is
functioning ok in section “Controller”. If that is ok, follow the
next steps.
When “no picture in AV”, first check if the video source
selection is functioning ok in section “Source Selection”. If that
is ok, follow the next steps.
1.
Check that normal operating conditions are met.
2. Check that there is video signal at pin 81. If no video,
demodulator part of the HERCULES is faulty, replace with
new HERCULES.
3. If video signal is available at pin 81, check pin 56, 57, and
58 for the RGB signal.
4. If signal is not available, try checking the BRIGHTNESS
and/or CONTRAST control, and make sure it is not at zero.
5. If still with the correct settings and no video is available,
proceed to the CRT/RGB amplifier diagram.
For sets with TDA9178, follow steps below:
1.
Put Option Byte 2 bit 4 to “0”; if video signal is not available,
then check fault finding section “Controller”, Section
“Source Selection”, and steps above.
2. If video is available but not correct, put Option Byte 2 bit 4
to “1”, then check if LTI panel is present. If not, put LTI
panel in the main chassis (connector 1221).
3. If LTI panel is in main chassis, check cable between LTI
panel and main chassis (position is 1206). If it is
connected, then the LTI panel is faulty, replace it.
For sets with Scavem, and Scavem does not work, follow steps
below:
1.
Check Scavem coil connector (position is 1361) if
connected; if not, connect it.
2. If connected, check NVM “bit storage” byte 1 bit 7; if it is not
“1”, set it to “1”.
3. If it is “1”, then check the data of the NVM addresses as in
the NVM default. If the data is not correct, then set these
addresses to diagram values.
4. If it still not works, track Scavem output from pin64 of
HERCULES to CRT panel.
5.8.8 Audio Processing
No Sound
Figure 5-13 Fault finding tree “No sound”
No RF audio for QSS/Inter-Carrier stereo sets.
1. Check pin 99 and 100 for SIF signal (for QSS) or pin 104
and 105 for video with SIF (for Inter-Carrier)
2. If signal is not present, check for the QSS/FMI bit settings.
Check also the NVM data.
3. If signals are present and still no audio, check the audio
supply v8V are present.
4. If still no audio signal at Hercules output, Hercules is faulty.
No AV audio.
1. Check troubleshooting methods in section “Source
Selection”.
2. Check the output of the Hercules to see if there is signal
available. If no, check the normal operating condition and
also the NVM data.
3. If still no audio signal at Hercules output, Hercules is faulty.
Note: If there is audio signal at Hercules output and no audio
at loudspeaker, proceed to Audio Amplifier troubleshooting
methods.
5.8.9 Audio Amplifier
No RF as well as AV audio at the loudspeaker:
1. Check that the normal operation condition of the amplifier
is met.
2. If normal operation conditions are met, check the continuity
from Hercules output to input of the amplifier.
3. If continuity is there and still no audio, check speaker wire
connections. If still no audio, amplifier IC might be faulty
Picture Ok,
No Sound
Tuner IF Ok Check Tuner/IF Not Ok
Check AUDOUTLSL &
AUDOUTLSR pin at
Hercules
Ok
Check Audio
Amplifier
Check Hercules IC
Check Audio
Power Supply
Check Audio
Amplifier Circuit
and loud speaker
Check Power
Supply
Replace Audio
Amplifier
Check NVM
Not Ok
Not Ok
Not Ok
Ok
Ok
Ok
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