电信机线设备由于其中某些焊头或接点的接触不良,常会发生性能不正常、质量下降等障碍.这类障碍是不稳定的:有时尚未进行查修,却已自行恢复正常;有时在检查测试过程中,障碍突然自行消失;有时甚至只要用手在机壳上敲击一下,就可使障碍消失,但是这时障碍往往仍潜伏在机线设备中,并未真正被清除掉,此后仍会继续不断地形成类似的障碍. Telecommunications line equipment due to some of the welding head or poor contact, often occur abnormal performance, quality degradation, etc. Such obstacles are not stable: sometimes not for repair, but have their own return to normal; sometimes check During the test, the obstacle suddenly disappeared on its own; at other times, even a hand-tap on the case made the obstacle disappear, but at this time the obstacle was still lurking in the line equipment and was not really cleared away Will continue to form a similar obstacle.