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故障现象:一台SANYO M 9500 K录音机,收音正常,在放音时,音量旋钮置较大位置时,扬声器中发出“嘟嘟”声,有时放音则正常,但拍拍机壳,此故障重现,并伴有类似会场上因声反馈引起的啸叫声。故障检修:此故障类似由于滤波电容不良引起的交流声,用电池代替,故障依旧。以为前置放大器滤波不良,经检查测试均正常。又想到是否电机接触不良产生跳火或机座接地不良以及静电干扰等因素,均未解决问题。后按动录音开关(REC)时,故障有所改变,反复按动并改变每次按动的幅度,故障消除。后振动机壳等,故障不再出现。打开开关,发现内部严重氧化并有接触松动现象,用无水
Symptom: A SANYO M 9500 K recorder, normal radio, the volume knob at a larger position, the speaker beep “beep”, and sometimes play is normal, but pat the case, the failure Reproduce, accompanied by a similar venue due to feedback caused by howling. Troubleshooting: This fault is similar to the AC noise caused by poor filter capacitor, with the battery instead of the fault still. Poor pre-amplifier that filter, the test were normal. Also think of whether there is a poor motor contact flashover or chassis grounding and electrostatic interference and other factors, did not solve the problem. After pressing the REC switch (REC), the fault has changed, repeatedly press and change the range of each press, the fault is eliminated. After the vibration case, the fault no longer appear. Open the switch, found that the internal serious oxidation and loose contact phenomenon, with water