Sharp CD-MPX870, Service Manual

Page: 83 / 112

CD-MPX870
7 – 4
The HF waveform is normal and the time is dis-
played normally, but no sound is produced. Or the
sound has dropouts.
(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 PDOUT waveform. (Figure 6)
Check around pins 26~30 on IC1.
Figure 6
T
FDO
PDO1
PDO0
Stopped
CH1=500 mV
DC 10:1
CH3=1 V
DC 10:1
CH4=1 V
DC 10:1
500 ms/div
(500 ms/div)
NORM:20 kS/s
1
4
3
=Record Length=
Smoothing : ON CH1 : 0.000 V
CH2 : 0.0 V Main : 100 K
Zoom : 2 K Mode : AUTO
Type : EDGE CH2
Delay : 0.0 ns
Hold off : 0.2 µs
CH3 : 0.00 V
CH4 : 0.00 V
BW : FULL
=Trigger= =Filter= =Offset=
CH1
v/DIV
500 mV
1999/04/05 17:33:17
(5) Others.
Is pin 35 (C2F) on IC1 "L" ? No There are too many error flags on a damaged disc which makes
error correction impossible.
Yes
1. When playing at normal speed.
Check the peripheral circuit at pin 69 (DOUT) on IC1 and the
waveform (Figure 7). Check again using a known good disc.
If OK, Check the unit.
Figure 7
T
T
DOUT
Stopped
CH1=2 V
DC 10:1
500 ns/div
1999/04/07 09:25:28
(500 ns/div)
NORM:200 MS/s
1
=Record Length=
Smoothing : ON CH1 : 0.00 V
CH2 : 0.00 V Main : 1 K
Zoom : 100 Mode : NORMAL
Type : EDGE CH1
Delay : 2.887 ms
Hold off : 0.2 µs
CH3 : 0.00 V
CH4 : 0.00 V
BW : FULL
=Trigger= =Filter= =Offset=