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red with shadow.
Analysis and troubleshooting: if colour has distortion in DVD state, trouble may probably lie in
SDRAM or Mt1389 or on CVBS output line. Switch from DVD state to SCART state firstly, picture colour
is normal, so colour has distortion before MST718 input. CVBS outputs from Mt1389 and then enter
MST718 through frequency selection network for image processing, so trouble should lie in frequency
selection network. Power off, use multimeter to check whether each resistor and capacitor element has
resistance sudden change, and R395/75Ù has sudden change with only 15-ohm, which is caused by the
large attenuation of the signals outputted from DVD. Change resistor with the same specification and
trouble is removed.
symptom: do not read DVD disc
Trouble description: in DVD state CD playing is normal, DVD playing is not available and then DVD
disc ejects out automatically.
Analysis and troubleshooting: firstly check whether DVD protection point of loader has joint welding
phenomenon and there is no abnormality. Change loader and trouble still exits,
so trouble lies in CD/DVD mode switch circuit. CD/DVD mode switch is controlled by pin 112 I/O
port level of Mt1389 and VRCD and VRDVD switch is realized through selecting drive circuit. When disc
switches in CD and DVD, the switch of IOA in high and low level means that Mt1389 control port outputs
normally. When IOA is low level, TRDVD should be low level and it is high level actually. Check R187
and circuit has disconnected because of rosin joint. Use iron to weld again and confirm and trouble is
removed.
[ Example 20 ]
shown in the figure
3.3.1.4,
figure 3.3.1.4
circuit diagram
CD/DVD mode switch