Fixing A Leaky Deca MIG Welder

All in all I'm pretty pleased with my welder, as I get more experience with it I find I can generally turn out pretty good work :). A big part of being able to turn out good work with a MIG is the ability to use shielding gas- with gas & a solid wire the weld runs a little cooler than with flux cored wire thereby reducing burn-through and there is virtually no splatter to clean up. The Deca welder I bought came equipped for gas out of the box & I quickly acquired a tank & regulator. One problem soon became obvious though- Deca uses a trigger operated valve in the handle to control the gas flow. Maybe its just my machine or maybe they just use cheap valves but the darn thing leaks gas when you aren't welding, you can actually hear the thing hissing. If its in a bad mood you can here it hissing from the other side of the room :(.
Heck, it isn't just a 'hiss", it's a *HI$$*- that's the sound of money diss-appear'n into thin air folks :(:(.
It wasn't so bad when I wasn't doing that much welding or working for extended periods, I'd just turn off the tank valve, but as I started moving into the body work repairs on our jeep "Tonka" it was becoming a bit of a pain so I decided to remedy the situation -




Here's the handle opened up to show the valve, you can see how the trigger pushes on the intermediate lever to operate the valve. The electrical switch controlling the welder itself consists of a brass rod on either side of the imtermediate that get shorted together by the brass pin visible sticking through the lever. I guess you get what you pay for :).




Welder-ectomy 101- The Beast Revealed.
Hmmm, getting rusty in there-
And Dirty.
Anyhow heres the plan- We're gonna add a solinoid operated valve into the gas line.




The hose barb on the rear panel. Nothing special, just standard 1/8" fittings.
I'll mount the valve to the rear panel simply by screwing the barb fitting into it




Looks like the best place to get the switched juice to run the valve is from the wire feed motor. Checking with the meter I find that the motor runs on 4 1/2 volts, I was pretty sure I wouldn't find a valve that operates at that voltage so I got a 110 volt unit & threw in a five volt relay to control it. Soldering on a couple of really spiffy looking red wires & we're off to the next step-




Finding some 120 to actually power the relay. Digging around with the meter I found the connections on the power switch that feed the control board. A couple of double terminated spade lug connectors & we have juice :).




The valve & relay installed. The valve has 1/4" fittings but a few adapters fixed that up. The 1/8" nipple is what I had in the junk pile, it's not that long on purpose.




A simple mod but one that works very well, the gas only flows when the trigger is pulled & theres absolutely no leakage now :). As an added bonus theres now a really cool "CLUNK" sound comes outta the machine whenever I pull or release the trigger :):). Total parts cost about $40, I'm sure I'll save that much on gas eventually but its already worth it because I don't have to bother turning off the tank anymore if I'm messing with something else for a few minutes & no more annoying *Hi$$ing* sounds.

And no more waking up at night wondering if I remembered to turn the darn thing off or if I'll have an empty tank in the morning :).




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