Sharp CD-PC3500, Service Manual

Page: 43 / 68

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CD-PC3500
If the level is not normal, check around pins 27~29 on IC1.
1. Is focus servo activated? (Waveform drawing 43-2) Pins 1~11 on IC1
Check the laser diode driver Q3 peripheral circuit.
Focus error circuit (pins 20 and 21 on IC1)
When a disc is loaded, start playback operation.
2. Does DRF change from "L" to "H"? Is the disc rotating?
3. Is the HF waveform normal? (Waveform drawing 43-3)
Check the spin system.
If the disc is spinning and a HF waveform is generated,
DRF will go H.
Figure 43-1
Check the laser diode driver Q3 peripheral circuit.
(1) Focus-HF system check
Although a CD is inserted and the cover is closed, "NO
DISC" is displayed.
1. Did the pickup move to the PICKUP-IN Switch (SW4)
position?
Sled motor (M2)
Press the OPEN/CLOSE switch (SW1) without inserting a
disc, and try starting the playback operation.
2. Does the focus (lens) move up and down?
(Waveform drawing 43-1).
Check the focus peripheral circuit.
3. Is the laser lit?
Spindle motor (M1).
4. Is the turntable rotating?
Figure 43-2
Figure 43-3
Yes
Yes
Yes
No
No
No
No
No
No
No
Yes
Yes
No
T
FDO
TDO
Stopped
CH1=500mV
DC 10:1
CH3=500mV
DC 10:1
500ms/div
(500ms/div)
NORM:20kS/s
1
3
=Record Length=
Smoothing : ON CH1 : 0.000V
CH2 : 0.0V Main : 100K
Zoom : 2K Mode : AUTO
Type : EDGE CH1
Delay : 0.0ns
Hold off : 0.2us
CH3 : 0.000V
CH4 : 0.00V
BW : FULL
=Trigger= =Filter= =Offset=
CH1
v/DIV
500mV
T
FDO
DRF
TE
Stopped
CH1=500mV
DC 10:1
CH2=10V
DC 10:1
CH3=1V
DC 10:1
500ms/div
(500ms/div)
NORM:20kS/s
1
2
3
=Record Length=
Smoothing : ON CH1 : 0.000V
CH2 : 0.0V Main : 100K
Zoom : 2K Mode : AUTO
Type : EDGE CH1
Delay : 0.0ns
Hold off : 0.2us
CH3 : 0.00V
CH4 : 0.00V
BW : FULL
=Trigger= =Filter= =Offset=
-3div -1div 0div +1div +3div
CH Position To
CH2
Position
0.20div
Vp-p=1.0V~1.3V
0.5mV/div,0.5
µ
sec/div