Sega Mark III Controller not working

[mxpxpxpx]

Hello, I recently purchased a Mark III that came with 3 controllers. One of them did not work. I took it apart and nothing looks out if the ordinary. I cleaned it and polished the contacts. The only other things I can think of is the cord is bad, the db9 connection is faulty, or I need to resodder the wires on the pc. All the wires are seem to be soddered and not loose. What should my next move be? I was aware the controller was broken when I bought the Mark III. Thanks for all the help.

[flo3ds]

Find a datasheet and check your circuit.

[SignGuy81]

Since none of the buttons are working the open is going to be the "common".

 

Unplug the controller, take it apart and check from pin 8 to inside the controller to the common wire, you should have continuity, if not then it is in the cord or plug. If so then follow the trace on the board in the controller for a break or bad solder joint where the wire is soldered to the board.

[SignGuy81]

This should help. https://allpinouts.org/pinouts/connectors/videogame/segamaster-system-sms-and-megadrive-joystick/

 

The controller plug is the female plug, so go by that diagram to know where pin 8 is where you will be connecting one lead of a multimeter. Then the other lead you will put on common/gnd wire in the controller and check for continuity.