Sharp XL-DK255 Service Manual - Page 55

Although a CD is inserted and the cover is closed, NO DISC is displayed., Focus-RF system check.

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(1) Focus-RF system check. Although a CD is inserted and the cover is closed, "NO DISC" is displayed. Press the Tray1 CD Eject Button without inserting a disc, and try starting the playback operation. 1 FDO IC1 22 2 TDO 23 IC1 XL-DK225 1. Does the pickup move to the PICKUP-IN Switch (NSW1) position? Yes 2. Does the focus (lens) move up and down? (Waveform drawing Figure 1) Yes 3. Is the laser lit? Yes 4. Is the turntable rotating? When a disc is loaded, start playback operation. 1. Is focus servo activated? (Waveform drawing Figure 2) Yes 2. Is the RF waveform normal? (Waveform drawing Figure 3) No Sled motor (NM2). Figure 1 No Check the focus peripheral circuit. No Check the laser diode driver Q1 peripheral circuit. No Spindle motor (NM1). No Pins 5~9, 11, 18 19 and 22 on IC1 Check the laser diode driver Q1 peripheral circuit. No If the level is not normal. 1 22 FDO IC1 3 TE 16 IC1 Figure 2 4 2 IC1 RFOUT Figure 3 7 - 2

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XL-DK225
7 – 2
Although a CD is inserted and the cover is closed,
"NO DISC" is displayed.
(1) Focus-RF system check.
Press the Tray1 CD Eject Button without inserting a disc, and try
starting the playback operation.
Figure 1
IC1
IC1
1
22
23
2
FDO
TDO
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 19 and 22 on IC1
Check the laser diode driver Q1 peripheral circuit.
Yes
2. Is the RF waveform normal?
(Waveform drawing Figure 3)
No
If the level is not normal.
Figure 2
IC1
IC1
22
16
3
1
FDO
TE
Figure 3
IC1
2
RFOUT
4