Sharp XL-70 Service Manual page 36

XL-70/70C
• Laser failure.
Is +6.2V applied to the emitter of Q861 ?
Is +5V applied to the collector of Q861 ?
Is +5V applied to the pin 62 (VDD) of IC802 ?
Is +5V applied to the pin 1 (VCC) of IC801 ?
Is 0V applied to the pin 57 (SEL) of IC802 ?
Is approx. 2V applied to the collector of Q801.
Check BI802/CNS802. If it is normal, the optical pickup is
faulty.
• Focus failure.
Does the optical pickup move up and down when the disc is
removed?
Is the following waveform output at the pin 43 (FEI) of IC802
when the disc is set?
Is the waveform shown above input at the pin 44 (SBAD) of
IC802?
IC801 is faulty.
Yes
Yes
Yes
Yes
Yes
No
Yes
Yes
Yes
pin 43
(FEI)
pin 48
(FOO)
pin 44
(SBAD)
Yes
Check the PWB pattern between pin 16 of CNS602 and emitter of
No
Q861.
Check the peripheral parts of IC804 and Q861.
No
Check the PWB pattern between collector of Q861 and pin 62 of
No
IC802.
Check the PWB pattern between collector of Q861 and pin 1 of
No
IC801.
Does the laser come on when pattern cut between pin 8 (SEL) of
No
IC801 and pin 57 (SEL) of IC802 ?
Yes
Check the PWB pattern between IC701 and IC802 (BUCK/CCE/
BUS0~3)
Check the peripheral parts of IC801 and Q801. If it is normal, the
No
optical pickup is faulty.
Check as stated in item "FOCUS SERVO SAWTOOTH WAVE
No
FAILURE".
Check the periphery of IC801 and BI802/CNS802. Is it normal?
No
Yes
The optical pickup is faulty.
Check the pattern between pin 13 of IC801 and pin 44 of IC802.
No
Check the periphery of IC801 and BI802/CNS802.
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