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Sharp SM-SX1 Service Manual page 36

1-bit amplifier
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SM-SX1/SX1W
Cont. from page 35
Is any 1-bit signal from Pins 27 and 33 of IC803 output
to RLY801?
Does RLY800 and RLY801 operate?
Check the wiring from CNP303 to CNP304 and
1-bit amplifying unit.
• 1-bit amplifying section check (Signal is output from CNP303 and CNP304 but it does not sound.)
Is any signal output form Pins 2, 3, 5 and 6 of ICA1?
(Fig. 33-1)
Are the waveforms of QA1 to QA8 correct?
(Fig. 33-3, Fig. 33-4, Fig. 33-5)
Are the waveforms of ICA4 to ICA7 correct? (Fig. 33-6)
Are the waveforms of QA9 to QA16 correct?
(Fig. 33-7, Fig. 33-8)
Is any signal output from CNWAM6 and CNWAM7?
Check the surrounding of the relay PWB.
• 1-bit amplifying section check (power trouble/protector activation)
Don't the protector activate together with drop of voltage
±22V if CNWAM4 and CNWAM3 are disconnected?
Does the oscillating circuit operate? Check Pin 9.
Check ICA4 to ICA7, CA36 to CA39 and RA53 to RA60.
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Check IC808, IC809, IC811, IC812 and IC813.
No
Check the operation of Q801 and Q802 and the wiring of
No
each to the microcomputer IC907.
Check the waveform of the input pin, ICA1, voltage supplied
No
to ICA1 and ICA1 oscillating circuit.
Check ICA2, ICA3, QA1 to QA7.
No
Check ICA4 to ICA7.
No
Check RA53 to FA60 and QA9 to QA16.
No
Check LA802 to LA808.
No
Check the soldering.
Recheck the main body section.
No
Replace ICA1.
No
Check CXA1 crystal and CA8, CA9.
– 36 –

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