Sharp MD-M3 Service Manual page 60

MD-M3/M1
(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 60-1)
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 60-2).
2. When recording at double speed
Check the peripheral circuit at pins 57~59 (DATA, DATACK,
LRSY) on IC2 and the waveform (Figure 60-3).
If both 1. and 2. are OK, check the MD unit.
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 60-2
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=
Smoothing : ON CH1 :
BW : FULL
CH2 :
CH3 :
CH4 :
No
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
1
LRSY
2
DATACK
T
3
DATA
=Filter=
Smoothing : ON CH1 :
BW : FULL CH2 :
CH3 :
CH4 :
– 60 –
1999/04/05 17:33:17
CH3=1V CH4=1V 500ms/div
DC 10:1 DC 10:1 (500ms/div)
NORM:20kS/s
=Offset= =Record Length= =Trigger=
0.000V Main : 100K Mode : AUTO
0.0V Zoom : 2K Type : EDGE CH2
Delay :
0.00V
0.00V Hold off :
Figure 60-1
1999/04/05 20:50:17
CH2=2V CH3=2V
5us/div
DC 10:1 DC 10:1 (5us/div)
NORM:100kS/s
CH3
=Offset= =Record Length= =Trigger=
0.00V Main : 5K Mode : AUTO
0.00V Zoom : 100 Type : EDGE CH3
0.00V Delay : 0.0ns
Hold off : 0.2us
0.00V
Figure 60-3
CH1
v/DIV
500mV
0.0ns
0.2us
v/DIV
2 V