Electricians/Electronics guys

[mopar head]

I built a pipe welding roll out machine and utilized a bead roller motor to power it.
The control box converts to DC I assume, has on/off switch, forward/reverse switch, with a footpedal for variable speed.
The unit works great and I have used it for years.
Here`s the mind boggler, I recently tried to Tig weld with it and the welder footpedal would move the motor without using the motor footpedal.
Why would my welder foot pedal move the machine?

 

[mopar head]

WAG?

 

[67Dart273]

No idea. Is it possible the welder was set up that way a purpose, AKA the tig pedal was designed to control speed with MIG, and power in TIG mode? Is there a function switch that is set differently? Would have to study the diagram, otherwise, and some of those are so poorly drawn, it's ????

 

[mopar head]

No idea. Is it possible the welder was set up that way a purpose, AKA the tig pedal was designed to control speed with MIG, and power in TIG mode? Is there a function switch that is set differently? Would have to study the diagram, otherwise, and some of those are so poorly drawn, it's ????

Hey Del. good to see you back.
The machine is an old school Lincoln Tig 300/300 and arc welder combo, probably 70`s era.
Not even compatible for a wire feeder afik.
One of those massive 800lb. hunks.
Only thing the roller motor and welder share at the same time is common service ground.
Tig pedal just varies amperage.
Motor pedal just varies speed. Just a potentiometer feeding to a circuit board.
Pressing both at the same time made the motor go faster than the motor pedal by itself.
Weird.
I used another welder with the lift arc function just to do the job.