This solution covers and may possibly help fix the Nokia 5130 with No network or dropping Signal problem. The solution below shows the RF circuit of the Nokia 5130 Xpressmusic device that where we can establish a check up procedures.
Note before doing any hardware troubleshooting, you may first try to restore the device firmware on any latest firmware available. If the software calibration did not fix the problem you may then proceed to hardware troubleshooting.
For a total No network signal shown on the device, check all the supply voltages across on its corresponding RF chips. If all the voltage readings were all okay, replace both PA and the RF chip alternately.