Sharp XL-DH20NH Service Manual page 49

( 1 ) Focus error system check.
Although a CD is inserted and the cover is closed,
" NO DISC " is displayed.
1. Does the servo supply is + 3.3 V?
2. Is it Open / Close function OK ?
3. Is Sled able to move to inner ?
4. Is the laser lit ?
5. Does the focus ( lens ) move up and down ?
6. Is the turntable rotating ?
7. Is it the CD Laser driver circuit OK ?
( 2 ) Audio do not operate normally
The RF waveform is normal and the time is
displayed normally, but no sound is produced.
Or the sound has dropouts.
1. Put a disc on DISC compartment.
2. When playback starts does the disc initialise ?
3. Are the RF signal level output from U302
pin no 21 and 33 ( 3.3V and 1.8V ) normal?
( Waveform drawing Figure 1 for CD )
4. Replace Servo PWB.
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No Check incoming jack supply AC ( 220V ).
No Check incoming power supply VCC ( +3.3V )
No Check Sled circuit, U304 ( Pin 28 ).
No Check SLE circuit, CD Laser circuits.
No Check U302 ( Pin 109, 3 ,4 ) and U304 ( Pin 1, 28 ).
No Check U302 ( Pin 2 ) and U304 ( Pin 26 ).
Check Spindle SLED circuit.
No
Check the CD Laser driver ( Q206, Q302, Q303 )
peripheral circuit.
No Repeat steps as Focus errror system check occurred.
No Is the objective lens of optical pickups clean ?
No Replace optical pickup mechanism unit.
6 – 2
XL-DH20NH
Yes