I have a 550 Roomba which I am trying to use. After removing the cover I found the PS2 female.
After destroying 2 mice I discovered the missing ground (comon) wire connection could be unnecesary by using the yellow wire as the gnd. The brown wire is used as the command (signal).
I can control the Roomba from EZ-bot, but fwd & left make the Roomba go forward. reverse & right make Roomba go in reverse. The speed control works.
What does the command (signal) line look like, when I looked at it on my O'scope all I saw was a +5v. I had both old and new selected.
Did you ever get your roomba working properly?