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.
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No
Yes
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.
T
Stopped
CH1=2V
DC 10:1
T
1
DOUT
=Filter= =Offset=
Smoothing : ON CH1 :
BW : FULL CH2 :
CH3 :
CH4 :
– 42 –
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
Delay : 0.0ns
0.00V
Hold off : 0.2µs
0.00V
Figure 42-1
1999/04/07 09:25:28
500ns/div
(500ns/div)
NORM:200MS/s
=Record Length= =Trigger=
0.00V Main : 1K Mode : NORMAL
0.00V Zoom : 100 Type : EDGE CH1
0.00V Delay : 2.887ms
Hold off : 0.2µs
0.00V
Figure 42-2