Sharp CD-MPX870W, Service Manual

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CD-MPX870W
7 – 2
Although a CD is inserted and the cover is closed,
"NO DISC" is displayed.
(1) Focus-HF system check.
Press the Tray1 CD Eject Button without inserting a disc, and try
starting the playback operation.
Figure 1
T
FDO
TDO
Stopped
CH1=500 mV
DC 10:1
CH3=500 mV
DC 10:1
500 ms/div
(500 ms/div)
NORM:20 kS/s
1
3
=Record Length=
Smoothing : ON CH1 : 0.000 V
CH2 : 0.0 V Main : 100 K
Zoom : 2 K Mode : AUTO
Type : EDGE CH1
Delay : 0.0 ns
Hold off : 0.2 µs
CH3 : 0.000 V
CH4 : 0.00 V
BW : FULL
=Trigger= =Filter= =Offset=
CH1
v/DIV
500 mV
1. Does the pickup move to the PICKUP-IN Switch (NSW1)
position ? No Sled motor (NM2).
Yes
2. Does the focus (lens) move up and down ?
(Waveform drawing Figure 1) No Check the focus peripheral circuit.
Yes
3. Is the laser lit ? No Check the laser diode driver Q1 peripheral circuit.
Yes
4. Is the turntable rotating ? No Spindle motor (NM1).
When a disc is loaded, start playback operation.
1. Is focus servo activated ?
(Waveform drawing Figure 2) No Pins 5~9, 11, 18 and 19 on IC1
Check the laser diode driver Q1 peripheral circuit.
Yes
2. Is the HF waveform normal ?
(Waveform drawing Figure 3) No If the level is not normal.
Figure 2
T
FDO
TE
Stopped
CH1=500 mV
DC 10:1
CH2=10 V
DC 10:1
CH3=1 V
DC 10:1
500 ms/div
(500 ms/div)
NORM:20 kS/s
1
2
3
=Record Length=
Smoothing : ON CH1 : 0.000 V
CH2 : 0.0 V Main : 100 K
Zoom : 2 K Mode : AUTO
Type : EDGE CH1
Delay : 0.0 ns
Hold off : 0.2 µs
CH3 : 0.00 V
CH4 : 0.00 V
BW : FULL
=Trigger= =Filter= =Offset=
-3 div -1 div 0 div +1 div +3 div
CH Position To
CH2
Position
0.20 div
Figure 3
Vp-p=1.0 V~1.3 V
0.5 mV/div,0.5 µsec/div