Sharp MD-C2 Service Manual page 70

MD-C2
• Check the tracking system.
Check the waveform of IC1 pin 7 (TE).
The waveform shown in Figure 70-1
appears, and the disc condition is too
slow in being displayed.
Playback is possible in TEST mode.
Data cannot be read.
• Check the spindle system.
Is playback performed without a disc?
Yes
The turntable rotates a little.
Yes
The turntable fails to rotate or rotates at high speed.
• Checking the VCO-PLL system.
Is playback performed with a disc?
Yes
Although the HF waveform is normal, TOC data cannot be
read.
0.5s
1.00 V
IC2 3 PDO
0.5s
1.00 V
IC2 16 FD
Figure 70-2
Tracking servo is inoperative.
Yes
Playback is impossible
Yes
although initialization is
possible.
Check the VCO-PLL system.
Yes
5ms
1.00 V
IC1 7 TE
5 ms
5.0 V
IC1 54 DRF
Figure 70-1
No
No
No
Stop -- > Play
As VCO freque-
ncy is locked at
4.32 MHz, voltage
of PDD rises and
stabilizes.
2
3
– 70 –
Check the periphery of IC1 pin 8 to pin
15, and IC3 to CNP2.
Yes
Normal jump is
Yes
impeded, and the
program top cannot
be reached.
4
3
The spindle driver is normal.
Check the periphery of IC1 pin 23 to pin 27, pin 39, pin 40, IC2 pin
12, pin 13, from IC3 to CNP3.
Check the PDO waveform of IC2 pin 3. (Figure 70-2)
Check the IC1 pin 43, pin 44, IC2 pin 3, pin 5, pin 7, pin 9, and pin
10.
Check the periphery
Yes
of IC1 pin 14.
Abnormal