Value on two ends of nerve line and nerve line jack is large; change nerve line jack XS301 and trouble is
removed.
Example 10 Symptom: not read disc
Description: not read any discs
Analysis and troubleshooting: not read any discs, observe laser head action carefully and find there
is no focus action; test focus signal outputted by decode chip and it is normal; this signal is m\normal
until 5888, so change 5888 of the same model, trouble is removed.
Example 11 Symptom: power not on
Description: +5V, +9V, -9V, +3.3V have no output
Analysis and troubleshooting: check power board and find each path voltage has no output; check
and find 220V voltage input is normal, and bridge rectifying circuit has no voltage output; use multimeter
to test fuse tube and it has open circuit; change fuse tube and trouble is not removed. Test Tc501 anode
and there is still no voltage output, fuse tube is burnt down; check 4 diodes of bridge rectifying circuit
and they are all normal, Tc501 has no abnormalities of liquid leakage and stricken through; test pin 1 and
8 of U501 (switch IC) and it has short circuit; this IC has been stricken through; after changing IC,
trouble is removed.
Example 12 Symptom: power not on
Description: +5V, +9V, -9V have output, but +3.3V has no output.
Analysis and troubleshooting: test each path voltage output of power board and find there is no
+3.3V voltage output; check C510, TC506, TC505, L507, D507 and they are all normal; check D509
cathode and find there is no voltage output; test D509 and there is open circuit; after changing D509,
trouble is removed.
Example 13 Symptom: HDMI has no output
Description: connect with HDMI and there is no display
Analysis and troubleshooting: test H601 and V601 signal on decode board and they are normal;
test H601 and V601 on high definition board and find H601 signal is not normal; test R701 and it has
open circuit; change R701 and trouble is removed.
Example 14 Symptom: noise appears when power on
Description: when power on, only right channel has a bump sound, after increasing volume, there is
current sound and sound quality is abnormal, and other channels are normal.
Analysis and troubleshooting: according to symptom, in audio signal outputted by right channel,
there is some DC component and trouble lies in audio part. Use multimeter to check right channel audio
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