Sharp MD-X7H Service Manual page 110

MD-X8H
• Check the tracking system.
Check the waveform of IC1 pin 7 (TE).
The waveform shown in Figure 74-1
appears, and no disc state appears soon.
Playback is possible in TEST mode.
Data cannot be read.
• Check the spindle system
Play operation is performed without disc.
The turntable rotates a little.
The turntable fails to rotate or rotates at high speed.
• Checking the VCO-PLL system.
Play operation is performed when disc exists.
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 74-2
Yes
Yes
Yes
5ms
1.00 V
IC1 7 TE
5 ms
5.0 V
IC1 54 DRF
Yes
Yes
Yes
Stop -- > Play
As VCO freque-
ncy is locked at
4.32 MHz, voltage
of PDD rises and
stabili- zes.
2
3
Tracking servo is inoperative.
Playback is impossible
Yes
although initialization is
possible.
Check the VCO-PLL system.
Figure 74-1
The spindle driver is normal.
No
Check the periphery of IC1 pin 23 to pin 27, pin 39, pin 40, IC2 pin
No
12, pin 13, from IC5 to CNP3.
Check the PDD waveform of IC2 pin 3. (Figure 74-2)
No
Check the IC1 pin 43, pin 44, IC2 pin 3, pin 5, pin 7, pin 10, and
pin 11.
– 74 –
Check the periphery of IC1 pin 8 to pin
15, and IC5 to CNP2.
Yes
Normal jump is
Yes
impeded, and the
program top cannot
be reached.
4
3
Abnormal
Check the periphery
of IC1 pin 14.