THOMSON MT31AS Service Manual page 21

Some of the sources
defeat
Check the relative
video signals circuits
Check crystal's
frequency and
the range of
voltage
The method of maintain single source (such as TV, AV etc) abnormal display: Firstly, check
the relative channel circuit's component whether have obviously short and virtual jointing. It is
need to use forehead method to deal with the covert reason. It is need to check Tuner's outputs
for TV source abnormal display. Because of Main IC's high degree of integration, all of the video
signals are transmitted to the back end after processed by main IC. All of the sources' abnormal
display may caused by the main IC's abnormal run. So it is need to judge the problem is caused by
the main IC or fore-end circuits. You can do like this: Put the good machine's TV/AV signal into the
bad machine's Main IC ,and put the bad machine's TV/AV signal into the good machine's Main IC.
If the problem follows the action, the problem is caused by fore-end circuits. If the problem not
follows the action, the problem is caused by the Main IC or the periphery circuits.
6.3. Abnormal sound
Abnormal display
Check the Main IC'
periphery circuits. Try
to upgrade software.
NVM reset. Change
main IC.
Service manual of MT31AS
All of the sources
defeat
Check panel
parameter; check
panel
Check the signal circuit
between main IC and LVDS
socket (resistance,
inductance and via holes);
Check LVDS lines; Measure
the resistance between each
pair of LVDS signals, and
check it whether is
100/120Ω or not.