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Analysis and troubleshooting: when the above trouble appears, firstly check whether loader flat
cable has loosened. Check whether plug on loader flat cable has been oxidated and it is normal, so we
doubt loader has trouble. Change loader and trouble is removed.
symptom: left and right channels are not balanceable
Trouble description: sound of left speaker is lower than that of right channel
Analysis and troubleshooting: if channels are not balanceable, software setup may probably have
trouble. Firstly reset TV part, trouble does not disappear, so we can judge that trouble lies in hardware.
Disconnect power and check impedance of left/right speaker and it is normal. Test when machine begins
to play DVD test disc normally. Connect pin 4, 12 of TDA7266, use oscillograph to observe the amplitude
of left/right channel output of TDA7266 and left channel amplitude is smaller than that of right channel
(note: now ground of oscillograph is connected with OUT- and detect head is connected with OUT+), so
trouble lies in TDA7266. Change TDA7266 with the same specification and trouble is removed.
symptom: do not read disc
Trouble description: in DVD state, CD/DVD disc cannot be read and then disc ejects out
automatically.
Analysis and troubleshooting: check whether loader components flat cable contacts well and there
is no abnormality; remove loader flat cable and check whether the contact position of plug and loader
clasp has been oxidated. Change loader but trouble still exists, so trouble should lie in main board.
Power on, switch in DVD state, observe disc reading condition of loader and main axis, focus, feed,
trace action is normal, but disc type cannot detected. Observe focus carefully and find object lens
twitters greatly, but cannot form slim light spot to shine on disc, so trouble may probably lie in focus
circuit. Check pin 24, 25 of focus feedback loop Ba5954 and resistance value of R390 is normal. Use
iron to heat C162, trouble disappears, so capacitor loses effect. Change capacitor with the same
specification and trouble is removed.
symptom: no DVD image
Trouble description: other working state of machine is normal, but DVD function cannot be used
normally.
Analysis and troubleshooting: as for this kind of trouble, firstly judge whether trouble lies in DVD
function circuit. Check Mt1389 power supply and it is normal, Mt1389 clock and reset signals are normal,
so we doubt FLASH program loses. Power on, switch in DVD state and use oscillograph to observe
whether FLASH pin has waveform. Remove FLASH, record program again and trouble is removed.
symptom: colour distortion in DVD state
Trouble description: in DVD state, when playing CD/DVD disc, sound output is normal but colour is to
[ Example 16 ]
[ Example 17 ]
[ Example 18 ]
[ Example 19 ]