Sharp CD-BA250 Service Manual page 42

CD-BA250/CD-BA2600
(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 42-1)
Check around pins 73~78 on IC1.
(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 52 (C2F) on IC1 "L" ?
1. When playing at normal speed
Check the peripheral circuit at pin 39 (DOUT) on IC1 and
the waveform (Figure 42-2).
If OK, Check the unit.
Yes
Stopped
CH1=500mV
DC 10:1
PDO1
3
4
PDO2
T
FDO
1
=Filter=
Smoothing : ON
BW : FULL
No
There are too many error flags on a damaged disc which
makes error correction impossible.
Check again using a known good disc.
Stopped
CH1=2V
DC 10:1
T
1
DOUT
=Filter=
Smoothing : ON
BW : FULL
– 42 –
1999/04/05 17:33:17
CH3=1V CH4=1V
DC 10:1 DC 10:1
=Offset= =Record Length=
CH1 : 0.000V Main : 100K Mode : AUTO
CH2 : 0.0V Zoom : 2K Type : EDGE CH2
CH3 : 0.00V Delay :
Hold off :
CH4 : 0.00V
Figure 42-1
T
1999/04/07 09:25:28
=Offset= =Record Length= =Trigger=
CH1 : 0.00V Main : 1K Mode : NORMAL
CH2 : 0.00V Zoom : 100 Type : EDGE CH1
CH3 : 0.00V Delay :
CH4 : 0.00V Hold off :
Figure 42-2
500ms/div
(500ms/div)
NORM:20kS/s
CH1
v/DIV
500mV
=Trigger=
0.0ns
0.2 s
500ns/div
(500ns/div)
NORM:200MS/s
2.887ms
0.2 s