For creating 13-pin connector I used this: one male DB15 for pins (ripped off of old nintendo/famicom console), hot glue gun, paper-ish scotch tape (for painting) and ordinary DIN connector from AT keyboard (huuge ps/2). Oh yeah, pliers, marker pen and scalpel.
Here are the parts prepared:



I just took out pins from DB15 connector with pliers and cut them to be equal. (a little measuring is needed so they don`t go too long). It is possible to use any simmilar connector, like for atari or commodore 64. The next thing I did is tearing apart keyboard`s connector with scalpel and just keeping metal tube-like part for case sheld. When everything is ready, a little circle of scotch tape is needed on atari`s connector so the glue will not stuck. Little cut pins are now applied in every hole of atari`s connector and all lined up:


It`s time for hot glue now. A little tape is needed around the connector for possible plastic leaking. The glue is applied from every angle and side so there are no air gaps. After cooling up it looks something like this:


I just removed extra plastic with scalpel and cleaned connectors for soldering. The connector is almost done but it needs housing. Any will work, even the original one that was cut off. After soldering wires housing needs to be filled up with hot plastic.
Here`s the finished connector:



It looks pretty much like real one....
I hope this helps people who can`t get original cable or connector. I can also post pics and info about making your own external power supply if anyone is interested. Cheers! (and sorry for my bad Eng)