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晶体管扩音机的小信号放大电路极少损坏,故障多出在功放级和电源部分。功放级故障又常是大功率功放管烧坏。有些机器更换功放管后,使用不多长时间,功放管又被烧坏。检修这种屡烧功放管的扩音机,不可对功效管一换了之,应分析并找出故障的根源后,再采取相应措施。一、屡烧功放管的原因分析常见功放管损坏的情况有两种:一是过电压击穿;二是过功耗烧毁。 1. 过电压击穿 (1)功放管质量不好,V_((BR)CEO)值太低:理论上说,功放管集电极承受的最大反峰电压为电源电压的2倍,为安全工作考虑,还应留一定余量。有些扩音机,
Transistor amplifier little signal amplification circuit damage, fault more in the power amplifier stage and power supply. Amplifier-level failures are often high-power amplifier tube burn out. Some machines replace the amplifier tube, the use of not long, the amplifier tube has been burned. Overhaul of this amplifier burning amplifier repeatedly, not a change of efficacy of the tube, should analyze and identify the root cause of the malfunction, and then take appropriate measures. First, the cause of repeated burning power amplifier tube Common power amplifier tube damage in two ways: First, over-voltage breakdown; Second, over-power burn. 1. Over-voltage breakdown (1) The power amplifier tube quality is not good, the V _ ((BR) CEO) value is too low: In theory, the maximum anti-peak voltage that the collector tube collector withstands is 2 times of the power supply voltage, Consideration, but also leave some margin. Some amplifiers,