I bought a samsumg galaxy i9295 second hand a month ago with no warranty and i have very bad signal almost all of the time even on 2g , but in very rare moments , like 2 times in a month the signal is how it should be ,but it reverse back to bad in some time , i disassembled the phone , it has no water damage or something , i tried to heat the motherboard with a hairdryer , i reflashed the phone rom and modem , repartition , but in vain.
The ussualy signal that i get is 85 dBm 14 ASU on 2g and 103 dBM 6 ASU on 3G , but in the moments when it get back to normal it have around 69 dBM 22 ASU on 2G and 77 dBm 18 asu on 3g , same as the other phones , but sadly that are very rare moments when i get this signal with this phone , and the phone is not usable in a place with middle or bad coverage , like in a elevator or in a country zone , it have even no emergency signal.
And another thing that i observed is that the wi-fi does not work if i have less than 3 lines at wi-fi signal , if i have less it no transmit data or is extremely slow, and the speed is decreasing drastically on 3 lines , only on 4 lines ( max ) it runs how it should.
What is the problem and how can i resolve it ? I think it has a faulty power amplifier IC , but i am not sure.