Sharp CD-C250X BK - Page 15

Check the Focus - HF svstem.
1 Playback can be performed without a disc.
I
I-
Yes
Focus search OK
No
Does the output waveform of ICi(lG)(FD) match that shown in
Fig. 15-i?
1 No
Check the area around IC5CNP2.
i
Check the IC1(50)(CLK) line, 4MHz.
Check the microcomputer data on pins (51)(CL), (52)(DAT) and
(53)CE.
0.5s
0.50 v
Cl @ FD
Focus search
is performed
two times
when play
operation is
done without
disc.
0%
0.50 v
ICl @TD
Figure 15-l
Check the laser diode driver.
Yes
Check the area around ICl(l6) - (21) (focus servo circuit).
Does the DRF signal change fr
Yes
No
If the disc is not turning, the DRF
should not change to “H”.
Check the spin system.
*~
Is HF waveform normal (see th
i
Yes
Check the periphery-of
ICl pins 41 and 42.
4
Check the tracking system.
Waveform is unstable. Check the spin system.
HF
O.lV/DIV
O.Susec/DIV(DC)
(When playing
back the disc)
Figure 15-2
0.5s
1 .oo v
ICl @ FD
0.5s
Waveform in
case of normal
play-back
Figure 15-3
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