Sharp CD-XP500 Service Manual page 42

CD-XP500/CD-XP5500
(1) Focus-HF system check.
Although a CD is inserted and the cover is closed, "NO
DISC" is displayed.
Press the OPEN/CLOSE switch (SW1) without inserting a
disc, and try starting the playback operation.
1. Does the pickup move to the PICKUP-IN Switch (SW4)
position ?
2. Does the focus (lens) move up and down ?
(Waveform drawing Figure 42-1)
3. Is the laser lit ?
4. Is the turntable rotating ?
When a disc is loaded, start playback operation.
1. Is focus servo activated ?
(Waveform drawing Figure 42-2)
2. Does DRF change from "L" to "H" ?
3. Is the HF waveform normal ?
Figure 42-3)
Stopped
CH1=500 mV CH2=10 V
DC 10:1 DC 10:1
FDO
1
T
DRF
2
TE
3
CH Position To
-3 div -1 div 0 div
=Filter= =Offset=
Smoothing : ON CH1 : 0.000 V
BW : FULL CH2 : 0.0 V
CH3 : 0.00 V
CH4 : 0.00 V
Figure 42-2
Yes
Yes
Yes
Yes
No
Is the disc rotating ?
Yes
(Waveform drawing
CH3=1 V 500 ms/div
DC 10:1 (500 ms/div)
NORM:20 kS/s
CH2
Position
0.20 div
+1 div +3 div
=Record Length= =Trigger=
Main : 100 K Mode : AUTO
Zoom : 2 K Type : EDGE CH1
Delay : 0.0 ns
0.2 µs
Hold off :
Stopped
CH1=500 mV
DC 10:1
T
FDO
1
TDO
3
=Filter=
Smoothing : ON
BW : FULL
No
Sled motor (M2).
No
Check the focus peripheral circuit.
No
Check the laser diode driver Q1 peripheral circuit.
No
Spindle motor (M1).
No
Pins 7~11, 79 and 80 on IC1
Check the laser diode driver Q1 peripheral circuit.
No
Check the spin system.
If the disc is spinning and a HF waveform is generated,
DRF will go H.
No
If the level is not normal.
– 42 –
CH3=500 mV
DC 10:1
=Offset= =Record Length= =Trigger=
CH1 : 0.000 V Main : 100 K Mode : AUTO
CH2 : 0.0 V Zoom : 2 K Type : EDGE CH1
CH3 : 0.000 V Delay :
Hold off :
CH4 : 0.00 V
Figure 42-1
0.5 mV/div,0.5 µsec/div
Figure 42-3
500 ms/div
(500 ms/div)
NORM:20 kS/s
CH1
v/DIV
500 mV
0.0 ns
0.2 µs
Vp-p=1.0 V~1.3 V