No signal or weak signal is the most common faults phones. In my experience, such as the Motorola 308-328c and gc87 other models, when examining the various parts of the antenna and did not find any problems, do not weld under the shield, but with rosin powder streaming into the shield, and then slowly to the hot air gun shield blew, should be uniform, after such treatment, the failure generally can be ruled out. 4KRservice manual download site
4KRservice manual download site
     Analyze the reasons for failure, I think mainly soldering quality. Can be seen with a magnifying glass, there are subtle cracks in the solder components, measured with a multimeter

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