What you achieve by doing this without damaging car fm modilator :-
1. Continue using in car
2. Use to hear music from sd card, usb pendrive
3. Auxillary input to connect mobile or any other device
Step 1: You Need a Car FM Modulator Thats Very Cheap
Step 2: Remove Tiny Screw on Back Side and Top Ring
Remove the top round by twisting it has metal tip, metal ring yhat holds two sides of plastic body together, fuse, and the bkack screw.
Step 3: Remove Back Cover
Find the positive point and negative point on pcb
Step 4: Solder Wires From Pin to Positive and Negative Points on Pcb
Before you Solder make a small hole 1 1/2inch from top for wire to go inside. And also so that the FM Modulator can fit into cars cigarette lighter socket. After you insert wire inside back cover hole, tie a knot so if any pulls wire it should get stucked inside.
Soldervtwo wires to positive and negative points on PCB.
Step 5: Close the Back Cover
Step 6: Enjoy Music
This way you upgrade your old music system using its fm radio into a SD card, USB Pen drive capable.