Does anyone have a more detailed wiring diagram of the System 12 Drive than is provided in the print? Or any additional info on it for that matter. I’d like to be able to probe the SCR firing signals with a scope. This is on an ibox controller but I think the drive hasn’t changed that much. The car runs down fine, inspect or auto, but trips on an SCR insufficient armature current fault immediately when trying to run up. I see no voltage at TP3, I’ve swapped the LGA and serial cable as Motion suggested. The SCRs in the direction bridge seem to test good with a meter so I’m thinking the DS card that fires the SCRs.

What is the motor field doing at start of motion? Have you zeroed our the drive settings manually and not just the auto tune? I believe they have a breakdown of the drive in troubleshooting section of the manual where they explain the layout of there boards. Shoot me an email tjuricekgn10@gmail.com

Have you checked the velocity encoder coupling? Had the same issue on a Motion that turned out to be a broken coupling that would run ok in one direction but fault in the other.

Thanks for the input, it was a current sensor on the DS card that fires the SCRs