论文部分内容阅读
例一,一台三洋4500 K立体声收录机收音时良好,播放磁带时,机内发出“卟卟”声,并且其音量可调,右声道VU表指针发颤。分析、检修:从故障现象看,很象是右声道放大电路自激所致,初步判断可能是音量电位器之前的前置放大电路。打开机盖,看电路板上的元件无明显损坏迹象,又鉴于收音时无“卟卟”声,于是用纯酒精清洗收/放开关,经清洗后,故障仍未消除。偶然间发现该机的立体声磁头已经换过,于是先将立体声磁头的四根引线断开,此时再开机,故障消除,至此已查明是新换磁头的问题。卸下磁头测量,其性能良好,重新焊接引线后,故障竟莫明其妙地消失了,为了证
Example 1, a Sanyo 4500K stereo tape recorders good radio, playing the tape, the machine issued “Porphyrin ” sound, and the volume is adjustable, the right channel VU pointer quivering. Analysis, overhaul: From the fault phenomenon, it is like the right channel amplifier circuit due to self-excitation, the initial judgment may be volume potentiometer before the preamplifier circuit. Open the lid to see the circuit board components no obvious signs of damage, but also in view of the radio no “porphyrin ” sound, so pure alcohol cleaning / release switch, after cleaning, the fault has not been eliminated. Occasionally found that the machine stereo head has been changed, so the first stereo head four leads disconnected, then reboot, troubleshooting, has been identified as a replacement for the new head problem. Remove the head measurement, the performance is good, re-welding leads, the fault actually disappear inexplicably, in order to permit