Chosen Solution
I replaced the screen and frame on a Sony Xperia X compact and since then when calling someone the other person sometimes can’t really hear me good, sometimes it works fine and a second later it is very quiet and just doesn’t work like it should. What could the problem be? I already took the phone apart again and looked if there was any dust or something between the microphone (I hope it was the microphone, on the bottom right side of the mainboard?) and the screen but I didn’t see anything. Is it even possible to replace the microphone?
I think you damaged your microphone when you changed your screen. You can dial the Sony test code ##7378423## in the dialer, and test the microphone. Sony x compact have two microphone, their position is next to the headphone jack and the usb port, you can see this Sony xperia x compact teardown video, the microphone is fixed on the motherboard, it is non-removable. If you need to replace the microphone, you need to bring your XA phone to the repair shop to replace.
The solution is: Do not use any adhesive tape on the underside when closing the back cover
I had the same problem and found the solution. The quiet microphone problem after screen replacing happened to me because I forget to put a little adhesive (its a little black square seal with a circular hole) that creates a sort of “tunnel” between the microphone (that is on the motherboard) and the hole in the front panel. Without this seal the sould of voice does not reach directly the microphone and so the voice appears very quiet. Look for Microphone Adhesive - 1301-7388 on google. I moved the adhesive from the old screen and now the microphone works perfectly.
I think that the microphone and bottom loudspeaker are in the same assembly, maybe you blocked the sound shaft in the screen replacement?
