Microphonic preamp - help please????

[MRecords]

Hello everyone,

i got a weird little problem. I never read about this so i start a new thread.

I build two channels ez1290 about a year ago in the same case. Everything worked from the beginning. Today i tried it again to make sure it works for the next session an got weird sounds coming from one channel. When i hit anywhere on or inside the case it translates to really heavy sounds. There is also a little hum and increased noise floor. Is it possible that a capacitor broke and got microphonic? Any help is much appreciated.

Thanks

 

[JohnRoberts]

I have seen passive components got bad and become microphonic, while noise in response to tapping around could just be a bad solder connection...

With the unit turned on and open.. tap around lightly with a pencil eraser or something not conductive and try to identify where the noise is coming from.

JR

 

[MRecords]

Thank you John!!

It was the 2N3055. Changed it now it works. The hum is still there and is about 10dB worse than on my other channel but i ask in the ez1290 build thread.

Thanks
Cheers