Sharp QT-CD180(BL) Service Manual page 19

• Focus servo sawtooth wave failure.
Is sawtooh wave output to the pin 66 (FOO) of IC802 ?
Yes
Is +8.1V applied to the pins 21 and 22 (VCC) of IC803 ?
Yes
Is sawtooth wave obtained between pins 17 and 18 of IC803 ?
Yes
1.5~2.5sec
Is sawtooth wave obtained between pins 3 and 4 of BI801/
CNS801 ? (as shown above)
Yes
BI801/CNS801 connection failure or optical pickup failure.
• Spindle motor clv servo failure.
Is following wave output to the pin 72 (DMO) of IC802 when
the Function is changed to "PLAY" from "STOP" ?
Yes
DMO
Is above wave obtained between pins 5 and 6 of IC803 ?
Yes
Is above wave obtained between pins 5 and 6 of BI803/
CNS803 ?
Yes
BI803/CNS803 connection failure or optical pickup failure.
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No
1.5~2.5sec
No
No
No
No
No
No
– 19 –
IC802 is faulty.
Check the PWB pattern of IC803.
Check the PWB pattern of IC803.
Check the PWB pattern between BI801/CNS801 and IC803.
Check the procedure in "HF ERROR".
If OK. IC802 is faulty.
Check the PWB pattern between pin 72 (DMO) of IC802 and pins
5 and 6 of IC803. If OK. IC803 is faulty.
Check the PWB pattern between BI803/CNS803 and IC803.
QT-CD180