Focus-Rf System Check - Sharp CD-DK890N Service Manual

CD-DK890N

(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. Does the pickup move to the PICKUP-IN Switch (NSW1)
position ?
2. Does the focus (lens) move up and down ?
(Waveform drawing Figure 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 2)
2. Is the RF waveform normal ?
(Waveform drawing Figure 3)
1
FDO
22
IC1
3
TE
16
IC1
Yes
Yes
Yes
Yes
Figure 2
1
FDO
22
IC1
2
TDO
23
IC1
No Sled motor (NM2).
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.
4
2
RFOUT
IC1
7 – 2
Figure 1
Figure 3