Topfield TF4000FI, Руководство по обслуживанию, Страница: 11 / 62

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5.2.6. No picture but the OSD works.
Possible Cause How to Check How to repair
1 Tuner problem If the signal level of the tuner is
very low, it may be a problem of
the tuner, antenna cable or
antenna. Check the antenna signal.
Check the tuner part.
2 No or bad LNB power
No or bad 22khz signal. Check the LNB power and
22khz signal on LNB in of the
tuner.
See LNB section of this manual.
3 The power of the tuner
has some problem. If the signal level of the tuner is
very low, check the voltage of
the U1.7 (tuner). It should be
about 30V. If not, check the SMPS and the
power path (include series bead (L5)
and capacitors (C7, C8) )
4 CPU (IBM39STB02500)
problem
If all the other things work
except the picture and sound, it
may be the problem MPEG
decoding. In this case, the
signal level and signal quality of
the information bar will be good.
5 Channel Data path
problem.
There is good RF signal level,
and good signal quality, but no
broadcasting is scanned. In this
case, it may be a channel data
path problem. Check the channel data path of the
Main Board.
5.2.7. No picture(and no OSD) and No sound
Possible Cause How to Check How to repair
1 CPU (IBM39STB02500)
problem.
In this case, the OSD have
some problems.
2 SMPS problem. Check the all the power of
power connector on Main
Board. Repair the power according to the
advanced function test .
5.2.8. No sound and good picture
Possible Cause How to Check How to repair
1 Audio DAC or OP Amp
problem Test the Main Board according
to the advanced function test.
Repair the Main Board according to
the advanced function test.
5.2.9. No picture(and no OSD) and good sound
Possible Cause How to Check How to repair
1 CPU (IBM39STB02100)
problem.
Test the Main Board according
to the advanced function test.