SSC-32 + Arduino + Major Power Problems = Dangerous Bot

Hi, i’m currently working on a Scout based mech with an SSC-32 and an Arduino Mega ADK.
The arduino is just to house the Inverse Kinematic code and send signals to the SSC-32.

Now for awhile it had been working correctly, but now it seems to be having problems…
Let me elaborate

If i turn on the VS power without turning on the VL the robot goes into a series of “seizures” I’ve been caught off-guard many a time and it is pretty dangerous.

Now i have a rechargeable 6v 1600mah pack for the VS power and a 9v for the logic. The 9v goes straight to the SSC-32, then to the Arduino.

When i turn the 9v logic on first, everything seems to work, but it’s like there’s not enough power for both boards, the arduino doesn’t transfer serial data, and the SSC isn’t receiving any data. The weird thing is, this used to work fine, no problems, i haven’t even changed the setup… 9v’s used to work, now the only thing that will power it correctly is if the 5v serial cable is plugged into the Arduino. I’ve tried multiple new 9v batteries… nothing seems to work

The seizures and 9v problems are killing this project, please help

I dont have a camera on hand, but this is the setup,
The 9v line is tied to the VL screw terminals, then two copper wires run out from the same terminal to the arduino…
the VS-in is at the screw terminals, the VL=VS jumper is removed

What you have written conflicts with what should happen in real life. You are saying you are powering only the logic, and the servos are moving like seizures. How can the servos move with no power? Post images, who knows what’s going on.

Its actually the opposite, when i power the servos without logic, the behave very erratically. I dont have a camera on hand, but i will post pictures when i do

induction on servo signal cable? Chinese servos? my MG995 also unpredictable when only power attached and signal cable is in the air but when plugged into SSC didn’t see that trouble.