here I show u , how to repair insert sim problem of okia 2700c & 5130c ( because both r same type of pcb)
there is no sim esd filter in this sets , sim card controlling circuit r in avilma. first we check vsim voltage 2.8v in linefilter L2704 from avilma( in first picture) .
vsim 2.8v supply from avilma.
if no voltage obtain or less voltage , first remove two filter chipcaps C2700 & C2702 .
after remove that two chipcaps we need to check vsim voltage again in L2704 . if still no voltage obtain or less go to second step.
in vsim voltage output line there is another twin filter capasitor C2220 , value 1.5mfd/6.5v . if it's damage or shorted then also insert sim problem aeries . (see in picture no three)
so remove that twincapasitor then check for vsim voltage . if still same then we need to change avilma.
simrst,simclk,simio line goes to avilma directly . so if vsim voltage is normal but can't detect sim by mobile then avilma should be faulty & we need to replace avilma with new one.
sometiems it's also due to loose solder joints under avilma . so before replace reball avilma then check.
I don't mention to check simcard tray or jacket (X2700) because it's a common issue.
please feel free to ask anything if u can't understand .