Microphone problem in Samsung S3770 can be solved by using simple steps. Before disassemble mobile first check mic hole in mobile case, if hole open and there is nothing then disassemble cellphone. First check mic continuity with digital meter, if mic gives correct continuity then check mic points on mobile motherboard. Trace any broken point with digital meter and make jumper with good quality jumper wire. Below in diagram all mic points are traced and marked with color lines, follow the diagram and make jumpers like diagram.
diagram source u2ugsm.com
Samsung Gt-s3770 mic points damage traced diagram to solve microphone problem.