Sharp CD-BA120 Service Manual page 38

CD-BA120/125
(4) PLL system check
When a disc is loaded, start play operation.
The HF waveform is normal, but the TOC data cannot be
read.
Check the PDO waveform. (Figure 38-1)
Check around pins 1~6 on IC2.
(5) Others
The HF waveform is normal and the time is displayed
normally, but no sound is produced. Or the sound has
dropouts.
Is pin 35 (C2F) on IC2 "L"?
1. When playing at normal speed
Check the peripheral circuit at pin 37 (DOUT) on IC2 and
the waveform (Figure 38-2).
If both 1. and 2. are OK.
T
Stopped
CH1=2V
DC 10:1
T
1
DOUT
=Filter= =Offset= =Record Length=
Smoothing : ON CH1 : 0.00V
BW : FULL
CH2 : 0.00V
CH3 : 0.00V
CH4 : 0.00V
Figure 38-2
No
Yes
1999/04/07 09:25:28
500ns/div
(500ns/div)
NORM:200MS/s
=Trigger=
Main : 1K Mode : NORMAL
Zoom : 100 Type : EDGE CH1
Delay : 2.887ms
Hold off : 0.2us
Stopped
CH1=500mV
DC 10:1
PDO1
3
4
PDO2
T
FDO
1
=Filter= =Offset=
Smoothing : ON CH1 :
BW : FULL CH2 :
CH3 :
CH4 :
There are too many error flags on a damaged disc which
makes error correction impossible.
Check again using a known good disc.
– 38 –
1999/04/05 17:33:17
CH3=1V CH4=1V 500ms/div
DC 10:1 DC 10:1 (500ms/div)
NORM:20kS/s
CH1
v/DIV
500mV
=Record Length= =Trigger=
0.000V Main : 100K Mode : AUTO
0.0V Zoom : 2K Type : EDGE CH2
0.00V Delay : 0.0ns
0.00V Hold off : 0.2us
Figure 38-1