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这台扩音机的故障现象是无声。经查功放1BG_8、1BG_(10)、1BG_(11)三个管的b、c结均开路。用同规格的管3DD15D换上,刚开机超载指示灯一亮又烧坏三个管。检测电源变压器输出电压为24V,属正常,但经全桥整流后变为36V(正常值应为25V),笔者以为这可能是空载引起的。查音量电位器才发现音量开到最大,可见,功放管是因过载而烧坏的。将音量关到最小,更换同型号的管子后,将音量慢慢开大,开至中间,再开就有过
This megaphone’s malfunction is silent. The power amplifier 1BG_8, 1BG_ (10), 1BG_ (11) of the three tubes b, c are open circuit. With the same specifications of the tube 3DD15D put on, just turn on the overload indicator lit and burned three tubes. Detection of power transformer output voltage of 24V, is normal, but after the full-bridge rectifier becomes 36V (normal value should be 25V), I think this may be caused by no-load. Check volume potentiometer only to find the volume to the maximum, we can see, the amplifier tube is burned due to overload. Turn the volume to the minimum, change the same type of pipe, the volume slowly open large, open to the middle, and then have had