SHARP QTCD141H
Service Manual

QT-CD141H/161H/162H
� Playback can only be performed when a disc is loaded.

Is the Focus servo active? (Can you hear it working?) No Yes

Check the laser diode driver. Check the area around IC801(16) - (21) (focus servo circuit).

Yes Does the DRF signal change from "L" to "H"? No Yes Yes Is HF waveform normal (see the Fig. 28-1, 2)? Yes Check the tracking system. Waveform is unstable. No
Level is abnormal.

If the disc is not turning, the DRF should not change to "H".

Check the spin system.

Check the periphery of IC801 pins 41 and 42. Yes
w

Check the spin system.

HF 0.1V/DIV 0.5µsec/DIV(DC) IC801 41 (When playing back the disc)

0.5s 1.00 V IC801 16 FD 0.5s 10.0 V IC801 12 CLV+ 0.5s 10.0 V IC801 54 DRF 0.5s 2.00 V IC801 7 TE

Waveform in case of normal playback

2 1 3 4

Figure 28-1 � Check the tracking system.
Check waveform of IC801 pin 7 (TE).

Figure 28-2

The waveform shown in Fig. 28-3 appears, and no-disc state appears soon.

Yes

Tracking servo is inoperative.

Yes

Check the periphery of IC801 pin 8 to pin 15, and IC803 to BI801/CNS801.

Play is possible in TEST mode.

Yes

The unit will be initialzed in Normal mode, but Yes it will not play back.

Normal jump is impeded, and the program top cannot be reached.

Yes

Check the periphery of IC801 pin 14.

Data cannot be read.

Yes
5ms 1.00 V IC801 7 TE

Check the VCO-PLL system.

4

5 ms 5.0 V IC801 54 DRF

3

Figure 28-3 � 28 �