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在维修工作中,常常查出发生故障的元器件,但因元器件特殊,一时买不到,使得机器不能及时修复。或者彩电大规模集成电路,仅是局部损坏,而绝大部分功能良好,只有个别功能失常。这时稍改电路,就能轻而易举地解决问题,使机器得以修复,现举二例供参考。 [例1]北京8316彩电遥控不能关机。判断故障位于遥控开/关机电路。该机遥控开/关机电路如图1所示。测微处理N_(101)(M50436—560SP)⑨脚遥控开/关机电压5.1V/2V(正常时5.1V/0V)。断开VD_(711)后,N_(101)⑨脚开/关机是5.1V/OV,电压正常。怀疑N_(101)⑨脚外围电路异常。查VD_(711)、V_(712)、V_(715)等元器件均无异常,判断N_(101)⑨脚内电路不能对V_(712)基极很好箝位,造成遥
In the maintenance work, often found faulty components, but because of the special components, can not be bought, making the machine can not be repaired in time. Or color TV large scale integrated circuits, only partial damage, and most of the good features, only individual dysfunction. At this time a slight change to the circuit, we can easily solve the problem, so that the machine can be repaired, citing two cases for reference. [Example 1] Beijing 8316 TV remote control can not be shut down. Judge the fault is located in the remote control on / off circuit. The machine remote control on / off circuit shown in Figure 1. Microprocessing N_ (101) (M50436-560SP) ⑨ foot remote control ON / OFF voltage 5.1V / 2V (normal 5.1V / 0V). After disconnecting VD_ (711), N_ (101) ⑨ feet on / off is 5.1V / OV, the voltage is normal. Suspected N_ (101) ⑨ foot peripheral circuit anomalies. Check VD_ (711), V_ (712), V_ (715) and other components without exception, determine N_ (101) ⑨ foot circuit can not V_ (712) base very good clamp, resulting in remote