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[ Servo Volume 2 ]
Troubleshooting when TEST mode check was OK.
DVD
During normal playback operation (TEST mode is OK)
(1) Neither picture nor sound is output
*
Cannot search
a).
Can the feed system be driven?
Check the waveform of control voltage W003.
Search results in a change of duty
(three values with 2.5V at the center)
(The figure is exaggerated.)
Check the waveform of CN101"1" and "2".
b).
Is kick available?
Check the control voltage waveform from TP251 (W001)
Check the waveform of CN101"22" and "23"
Although differs in amplitude and DC offset, the waveform is similar to that of W003.
Kick pulse
*
NG after DEM/ECC (IC351, etc.)
Approx.
2.5V
Long-distance seek
Hold (DC) during feed
Line between IC301 and W003 or TP253.
After the driver (IC251)
For short-distance search, the waveform
becomes roundish, not trapezoidal, and
voltage is low.
From IC301 to W001
After the driver (IC251)
Acceleration pulse at start;
deceleration pulse at stop
(each one)
(In the direction of search,
opposite to this figure)
Feed
Tracking
Kick pulse (fine seek) is
inserted after long-
distance seek.
(Not one)
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