Mitsubishi RV-6SDL Robot arm Servo/Encoder usability

Generally speaking your chances of getting usefull information for and eventually actually repairing the controller are _very_ slim.
My controller has 3 identical IGBT modules (with driving electronics on board) and one was broken. I swapped one of the working modules in for the broken one and the controller would then no longer accept the modules even if I swapped them back into the original places.
There is likely some sort of diagnostic/configuration software required to service these controllers. It's all extremely proprietary and secretive.

The only thing of use from the original controller turned out to be some of the connectors, the safety relay assembly and the information extracted from the eeprom from which dmitry could then derive the motor settings to get the motors running using regular mitsubishi motor drives.

Your controller had a separate doughter board for the encoder feedback (the long one with the connectors on top left of the IGBT modules)?

As I recall, the encoders were connected to the main board. The daughter board you are referring to had a couple dozen capacitors on it so it must have been (at least partly) used for the power stage. Lots of processors/FPGA chips on the other side of it though. The driver boards also had processors on board. There is likely extensive serial inter-processor communication/ startup configuration going on so it its highly unlikely you would be able to reuse the drives from the controller without _very_ extensive reverse engineering.
Also, as you and dmitry already noted there seems to be very close integration of the drivers into the controller to achieve features like 'compliance'. 

DAMN that looks like something from "Star Wars" movie !
Probably very old Kuka robot, so
Do you have the control box for it?
Does it have 320 written on the box or hand controller?
What motors does it use?
Does it have encoders or resolvers on the back of the motors?
When did it have the gearbox oil changed?
Does it have a spring or hydraulic counterbalance?
Edit:
Start a new topic for it, if you already did not.
Thank you.

My interest was more pick and place and I have little experience with welding so I really do not know what can be achieved. However, I'd say, apart from relatively simple 3d paths, you would have a rather hard time to create gcode that would give you constant torch orientation along a more complex 3d path that also gives you constant speed.

My first question would be, how do you intend to create the gcode? A straight line or an arc in 3d space should be relatively easy but following a pipe joint would likely require a CAM of some sort. Also with a robot you really need to simulate the code to check for problems with singularities.

What I would recommend is this:

- take one of the available robot simulation configs and see if you can actually get what you want with that. If you cannot get it to follow the paths you need then there is really no point in going further

- If you think the software can get you where you want to go then you would need to figure out how to get the motors of the robot to run.

@Ehsan,
Start a new topic for the robot.
Thank you.