Sharp CD-MPX870W, Service Manual

Page: 82 / 114

CD-MPX870W
7 – 3
Check the TE waveform at pin 16 on IC1.
(2) Tracking system check.
If the waveform shown in Figure 4 appears and soon after NO
DISC appears ?
Yes
The tracking servo is not activated.
Check the peripheral circuits at pins 15, 16 and 23 on IC1,
and FFC1.
No
"Initialization" is possible, but play is not possible ?
Yes
A normal jump operation cannot be completed or the begin-
ning of the track cannot be found.
Check the around pin 23 on IC1.
No
"Initialization" is not possible. Data cannot be read. Check the VCO-PLL (Pin26~30 on IC1)
system.
Figure 4
T
T
TE
DRF
Stopped
CH1=10 V
DC 10:1
CH2=1 V
DC 10:1
100 ms/div
(100 ms/div)
NORM:100 kS/s
2
1
=Record Length=
Smoothing : ON CH1 : 0.0 V
CH2 : 0.00 V Main : 100 K
Zoom : 2 K Mode : NORMAL
Type : EDGE CH1
Delay : 2.924 ms
Hold off : 0.2 µs
CH3 : 0.00 V
CH4 : 0.00 V
BW : FULL
=Trigger= =Filter= =Offset=
(3) Spin system check.
Press the OPEN/CLOSE switch without inserting a disc, and
then try starting the play operation.
1. The turntable rotates a little ?
(Waveform drawing Figure 5) Yes The spin driver circuit is OK.
No
2. The turntable doesn't rotate. Check around pin 25 on IC1, pins 5 and 6 on CNP2.
Figure 5
T
T
PDOUT 0
PDOUT 1
Stopped
CH1=200 mV
DC 10:1
CH2=500 mV
DC 10:1
500 ms/div
1999/04/07 09:51:15
(500 ms/div)
NORM:20 kS/s
2
1
=Record Length=
Smoothing : ON CH1 : 0.000 V
CH2 : 0.000 V Main : 100 K
Zoom : 2 K Mode : NORMAL
Type : EDGE CH2
Delay : 2.924 ms
Hold off : 0.2 µs
CH3 : 0.00 V
CH4 : 0.00 V
BW : FULL
=Trigger= =Filter= =Offset=