Hi, I have a problem that is getting worse with my Snap On welder. It is made by Century. I love this welder, because it does everything I ask of it. Lately, like the last year, it has been sticking in the " On " position. Like if I would pull the trigger on the gun, the loud hum will continue, even if I release the trigger. Some times when I turn the power switch on, it will do the same thing. Is there a contactor of some sort that is NOT releasing ? It takes re arching to stop it, or just to turn it off and turning the machine back on. Sometimes it will do it over and over and get real frustrating. Other times it will do it and them not for a day or so. It sounds like something it sticking and won't release, but it is in the " weld " mode, if that makes sense. I don't know if the internal workings of a welder, but it something that is sticking or hanging up inside the machine.

 

Welcome to the forums.

Do you have a meter and know how to use it ?
I can forward you the schematic but it will require making checks on the board.

 

Sounds like the gun itself is bad, there are internal switches but like everything else they wear out!

 

I first suspect the switch in the gun sticking.

 

OK, but when I press the switch the wire comes out and it seems to work well in the regard.

 

The diagram is the control board. The two pins with red arrows are the trigger connection. You could monitor those with a voltmeter when the system is on or connect an ohmmeter with the system unplugged to check for shorts. A short on those two pins is what activates the switching contactor.

The pdf below is the schematic.