Old UNO MIG Follow-up

[Spit]

Here are the photos of the 1986 UNO MIG. it was made in 1986 and was made in Italy and has the Chicago Tool name on it. It is 120 volt and I would guess it is 80-90 amp output although it doesn't give any type of rating on the unit.. (It is very similar in externally to the new 90 Amp units that Harbor Freight sells with the Chicago Tool name today in most every way size, shape color etc)) Unlike the newer HF units..this has 2 seperate transformers in it.

It is a MIG unit and has a gas line that runs to the gun, I do not have a Argon tank or regulator and would like to switch it to a Flux Core Wire unit. I am looking for advice on converting the polarity to use it with flux core.

I can see that the hot line to the gun is attached to the rectifier with a nut and bolt. and the the ground clamp line is attached to a very heavy winding wire of the smaller of the 2 transformers.

I am assuming that I can switch therse 2 lines and be okay...
Can anyone confirm this? or give me any advice.

Thanks

Spit

 

[Doc Sprocket]

Logically, yes. I cannot confirm this, as I am not an electrical engineer, and every welder that I've had my head in just has two big terminals that you swap the wires on. If something turns up, I'll let you know.

EDIT- I just had a look at a Lincoln Electric wiring diagram, and this all sounds about right. Exercising common sense and good safety practices, go ahead and switch them around and test. Please do note that the capacitor (big cylindrical thing in there) can hold on to a fair bit of juice for awhile- either safely discharge it, or avoid it like he//.

 

[Spit]

Thanks for the reply. I did switch the wires and it does weld...but the wire feed no longer works. I assume that since the torch is now connected to the ground, there is no hot wire for the wire feed motor. I need to find a way to get a hot line to the switch.. Do you have any ideas?

I don't know if there is any way to switch the wiring to the motor? I wish I could identify who made it and get a owners manual and wiring diagram.

I took the torch apart and I can see that the switch is spring loaded and when pressed a metal shaft comes in contact with the torch body. It looks like the Argon gas line goes into the switch body? so maybe the button/switch is both a valve for the gas and electrical switch for the feed motor. I am mulling over ways to run an additional (hot) wire thru the casing to the torch and make it work that way..

Any ideas you might have would be apreciated.

Thanks
Spit

 

[Doc Sprocket]

Ouch- Yeah- I have heard of those units with the gas valve actuated by the trigger. Frustrating.

I think at this point, I would assess the motor (likely low voltage but further research required) and just tape a pair of wires all the way up to the gun switch to actuate the motor.