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Disassemble, powered on after startup, refer to figure 6 use oscilloscope checks at the C240 no Lo error voltage signal into a pulse waveform, amplitude is 2.4V. Check the error of two vibration-voltage signal at the C207, only about 0.1V, abnormal suspected U201 if module cold solder joint or damaged, remove the rear U201 A9 foot virtual pad fell off, C207 A9 feet with a fly line wiring, replace U201, turn signals, and troubleshooting.7hLservice manual download site
Summary: in this case is the second local oscillator phase-lock loop circuitry error control voltage anomalies; making it impossible to have a normal second local oscillator frequency signals, causing cell phone no signal.
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