(1) the multimeter to measure IC681 attending foot voltage 0.5 V, normal, using the oscilloscope to observe the feet, no stimulation waveform, suggests that fault. IC681 10 feet before a push or oscillating circuit. FTQservice manual download site
FTQservice manual download site
(2) measuring IC701 12 feet voltage of 10.3 V, the power supply voltage is normal. Check the oscillator R602 peripheral component, R603, C604, are no exception. Doubt is IC701 internal damage. FTQservice manual download site
(4) new LA7801 scanning, machine back to normal. FTQservice manual download site
(5) under the condition of no oscilloscope, also can use multimeter dB gear measuring IC701 attending foot presence of ac voltage, to determine whether to start up.FTQservice manual download site
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