DragonmasterDan made me hep to this, remembering an issue that I had long forgotten about.
I bought a Cable from the British Guys, Retrogamingcables.uk from them for PVM 2030A, and now that you mention It I'm still on their f*cking mailing list.
I had to do some soldering to make it work, they sent me a JP21 cable and I had to disassemble it and double-check with mickris and thesteve to rewire it so that it would work. I was kind of pissed off that I had to do the work over after having it shipped halfway across the world. Although, it was better than having green and blue messed up.
Anyway.... Yeehaw... the cable works. I still use it on the 2030A. But you may have to have a soldering party to get it to work.