NOKIA 6300 display problem.
 

I got Nokia 6300 with a display to be replaced. I replaced it, gave it to a friend. He came back to me saying that during incoming and outcoming calls and sending or receiving smses, the display pulsates. I realised, that the frequency of pulse is the same as the frequency of the calls' signals heard for example in a computer speaker. The question is: How to deal with it? Please, help. Regards P.S. Maybe the phone has been dropped, I don't know.

try to replace with another working lcd , then check.