Sharp CD-PC1881V Service Manual page 43

• Check the tracking system.
Check waveform of IC1 pin 7 (TE).
The waveform shown in
Fig. 43-1 appears, and no-
disc state appears soon.
Play is possible in
TEST mode.
Data cannot be read.
• Checking the spin system.
Play operation is performed without disc.
Yes
The turntable rotates a little.
No
The turntable fails to rotate or rotates at high speed.
• Checking the VCO-PLL system
Play operation is performed when disc exits.
Yes
Although HF waveform is normal, TOC data cannot be read.
• Although HF waveform is normal and the time
indication is normal, no sound is emitted.
Check IC 2 pin 48 (EFLG).
Check IC2 pins 37, 40.
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Tracking servo is
inoperative.
Yes
The unit will be initialized in
Yes
Normal mode,but it will not
playback.
Check the VCO-PLL system.
Yes
Yes
Yes
Yes
No
Yes
– 43 –
Check the periphery of IC 1
pin 8 to pin 15, and IC 3 to
Yes
CNP2.
Normal jump is impeded,
Yes
and the program top
cannot be reached.
5ms
1.00 V
IC1 7 TE
5 ms
5.0 V
IC1 54 DRF
Figure 43-1
The spin driver circuit is normal.
Check the periphery of IC1 pins 23 to 27, pin 39, and pin 40, IC2
pin 12 and pin 13, IC3 to CNP3.
Check PDO waveform (Fig. 43-2).
Abnormal
Check the IC1 pins 43 and 44, IC2 pins 3, 5, 7, 10, and 11.
0.5s
1.00 V
IC2 3 PDO
0.5s
1.00 V
IC2 16 FD
Figure 43-2
Usually, the number of pulses of flawless disc is 100 pulses/sec
or less.
CD-PC1881V
Check the periphery
of IC 1 pin 14.
Yes
4
3
Stop --> Play
As VCO freque-
ncy is locked at
4.32 M Hz, voltage
of PDO rises and
stabilizes.
2
3