No Picture But The Osd Works; No Picture(And No Osd) And No Sound; No Sound And Good Picture; No Picture(And No Osd) And Good Sound - Topfield TF4000FI Service Manual

5.2.6. No picture but the OSD works.

Possible Cause
1 Tuner problem
2 No or bad LNB power
No or bad 22khz signal.
3 The power of the tuner
has some problem.
4 CPU (IBM39STB02500)
problem
5 Channel Data
problem.

5.2.7. No picture(and no OSD) and No sound

Possible Cause
1 CPU (IBM39STB02500)
problem.
2 SMPS problem.

5.2.8. No sound and good picture

Possible Cause
1 Audio DAC or OP Amp
problem

5.2.9. No picture(and no OSD) and good sound

Possible Cause
1 CPU (IBM39STB02100)
problem.
How to Check
If the signal level of the tuner is
very low, it may be a problem of
the tuner, antenna cable or
antenna.
Check the LNB power and
22khz signal on LNB in of the
tuner.
If the signal level of the tuner is
very low, check the voltage of
the U1.7 (tuner). It should be
about 30V.
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.
path 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.
How to Check
In this case, the OSD have
some problems.
Check the all the power of
power connector
Board.
How to Check
Test the Main Board according
to the advanced function test.
How to Check
Test the Main Board according
to the advanced function test.
Check the antenna signal.
Check the tuner part.
See LNB section of this manual.
If not, check the SMPS and the
power path (include series bead (L5)
and capacitors (C7, C8) )
Check the channel data path of the
Main Board.
Repair the power according to the
on Main advanced function test .
Repair the Main Board according to
the advanced function test.
11
How to repair
How to repair
How to repair
How to repair