samsung e715 low signal or sometimes no network

[lesansan]

Hello all;
I have a samsung e715 sometimes i get signal and sometimes no signal bar , i have another e715 the signal is fine .. so i dont think service carrier problem..please give me any advise hoe to fix it...thank you all.

[MTi-GsM]

look the filter
50% problem will be sloved.......

[lesansan]

i am new to phone repair cant you tell me where is the filter at? thanks...