3.3.1 Servicing cases
[ Example 1 ] Symptom: DVD has no sound output
Description: disc read is normal, image output is normal, DVD playing has no sound output and
other external inputs are normal.
Analysis and troubleshooting: according to trouble symptom, trouble may lie in DVD board and audio
jack part. Firstly check whether pin 18/19 of video main board CN112 has audio waveform and then can
judge trouble lies in DVD board. Check pin 18/19 of DVD board XS103 and find that there is no audio
signal waveform.
Test TC240/TC241audio waveform and it is normal, so we judge trouble lies in U209 and peripheral
elements. Firstly check power supply of U209 and find that +12V has no power supply. Test pin 2 Xs101
according to line and there is still no +12V power supply. Check pin 5 of subsidiary power amplifying
board J3 and find that +12V power is normal, so we doubt flat cable from power amplifying board to main
video board has trouble. Change flat cable and trouble is removed.
[ Example 2 ] Symptom: disc tray ejects out automatically
Description: after power on, load disc and disc tray ejects out automatically.
Analysis and troubleshooting: connect with video terminal, power on and load disc. After disc tray
ejects in, TV screen displays “Loading” and then “Eject” after about 9 seconds. Disc ejects out, use
DVD, CD, VCD disc to test and this phenomenon still exists, so we doubt pick-up has trouble because of
aging and cannot read disc. After changing loader, trouble is removed. (If slot-in loader cannot read disc,
disc will eject out automatically)
[ Example 3 ] Symptom: do not read USB
Description: after machine switches in USB state, it dies not read USB but other functions are
normal.
Analysis and troubleshooting: Use multimeter to test USB terminal and find grounding and
+5Vvoltage are both normal. Use multimeter to test line from USB card board to DVD board and it is
normal, so we doubt 1389HD has trouble. Change 1389HD and trouble is removed.
Section Three Servicing Cases
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