Sharp MD-MX30 Service Manual page 70

MD-MX30/MX30W
(2) Tracking system check
Check the TE waveform at pin 18 on IC1.
If the waveform shown in Figure 70-1 appears and soon after
NO DISC appears.
"IL" is possible, but play is not possible.
"IL" is not possible.
(3) Spin system check
Press the LID switch without inserting a disc, and then try
starting the play operation.
1. The turntable rotates a little. (Waveform drawing 70-2)
2. The turntable doesn't rotate.
Yes
Yes
Yes
No
The tracking servo is not activated.
Check the peripheral circuits at pins 18 and 19 on IC1, pin 23 on
IC2, and Bi2.
No
A normal jump operation cannot be completed or the beginning of
the track cannot be found.
Check the around pin 23 on IC2.
No
Data cannot be read. Check the VCO-PLL system.
Stopped
CH1=10V CH2=1V
DC 10:1
TE
2
DRF
T
1
=Filter= =Offset=
Smoothing : ON CH1 :
BW : FULL
CH2 :
CH3 :
CH4 :
No
Check the spin driver circuit.
Yes
Check around pin 25 on IC2, pins 27 and 28 on IC3, and BI3.
Stopped
CH1=200mV CH2=500mV
DC 10:1
T
FDO
2
SPDO
1
=Filter= =Offset=
Smoothing : ON CH1 :
BW : FULL CH2 :
CH3 :
CH4 :
– 70 –
T
100ms/div
DC 10:1 (100ms/div)
NORM:100kS/s
=Record Length= =Trigger=
0.0V Main : 100K Mode : NORMAL
0.00V Zoom : 2K Type : EDGE CH1
Delay : 2.924ms
0.00V
0.00V Hold off : 0.2us
Figure 70-1
T
1999/04/07 09:51:15
500ms/div
DC 10:1 (500ms/div)
NORM:20kS/s
=Record Length= =Trigger=
0.000V Main : 100K Mode : NORMAL
0.000V Zoom : 2K Type : EDGE CH2
Delay : 2.924ms
0.00V
0.00V Hold off : 0.2us
Figure 70-2