I was just pocking my finger here and there to find out the the problem and i cam across how to find bad part in an amplifier! this technique is used in tube amp to find bad tube with a stick but in a solid state it works with bare fingers and even without touching the part, just bringing the finger near part makes increases the intensity of sound and that is how you can make out where is the problem! if i am wrong correct me, i will learn!
![](https://i.ytimg.com/vi/bFPQJWi5Yns/maxresdefault.jpg)