[ Example 4 ] Symptom: do not read DVD disc
Description: CD disc read is normal, after loading DVD disc, it ejects out automatically.
Analysis and troubleshooting: use multimeter to test Q302 and transmitter electrode voltage is
3.3V,which is normal; collector voltage is 2.2V and it is normal. Test inductor L312 between collector
electrode and pin 23 of Xs301and find inductor has open-circuit. After changing inductor, trouble is
removed.
[ Example 5 ] Symptom: DVD has no output
Description: DVD has no output and other functions are normal.
Analysis and troubleshooting: check voltage inputted by power amplifier board and it is normal.
Check 27M clock circuit and it is normal. Check U206 output circuit, and find there is only 1.4V and core
voltage is abnormal (1.9V when in normal cases). After changing U206, voltage is normal and trouble is
removed.
[ Example 6 ] Symptom: DVD has no image
Description: DVD disc read is normal, but no image output. After switching in TV state, image output
is normal.
Analysis and troubleshooting: according to trouble symptom, trouble lies in DVD part. Test
component video signal on DVD board XS103 and find brightness signal in the three-channel signals
Xs103 has no output, shown in the figure 3.3.1.1,test L229 and find this inductor has no signal output.
Test resistor to ground of this circuit and it is 0-ohm,so we doubt C295 has electric leakage. After
changing trouble is removed.
Figure 3.3.1.1 Video output circuit
R249
75R
YUV4
C295
121
L229 1.8uH
C290
121
R214
75R
VIDEO G/Y
Tc121
100uF/16V
Tc122
100uF/16V
VIDEO Y1
VGND
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