Problem with TIG welder HELP!!!!!

[awoo]

just got back from using my welder and the gas has stopped coming out, bought 2nd hand on ebay at great cost so this has not got me happy...

its a selco 202 tig ac/dc welder. finished using it and (perhaps wrongly) closed the tap on the argon bottle and pressed the foot pedal to let the gas out, so there is no pressure sitting in the system. did this, the regulator went down then juddered. pressed the foot pedal again to let the gas out and nothing happened.

opened the gas bottle up again and tried to weld a little to see what was going on and no gas is now coming out.

tried switching it on an off but no joy. let off the hose a little and gas comes out of there so i know the regulator is not jammed.

guessing it is the solenoid in the welder itself. I'm just hoping that i havnt burnt anything out by pressing the pedal down a few times to let the gas out. i was just holding the torch, it wasnt pointed at anything. i thought this was ok to do as i was taught to do this to check if gas comes out.


i have read it might just be a stuck solenoid and a sharp tap might sort it. theres loads of gas in the bottle, it tries to weld and the foot switch turns on the water pump so that side is ok, its just the gas...

any ideas? been filled with horror stories of expensive welders crapping out and needing new circuit boards etc, got me worried

[skylinedave]

You will not have knackered it by pressing the pedal thats for sure . It does sound like the solenoid has stuck or it may be the pedal . Did it try to arc up with no gas ?


Pedals can be a real problem sometimes , a lot of people by exchange from welding suppliers and we used to have real problems with them . All they would do is open them up and nip up a worn out nut , paint them and stick some more grip tape on the top . A few weeks later they would come undone again and we could not do anything as we were not allowed to fiddle with them .


Sounds like the solenoid anyway .

[93fxdl]

Had the opposite with a mig welder, the solenoid stuck open, giving constant gas flow, a few swift taps sorted it. Hope your fault is cured as easily.
Ttfn Glenn

[awoo]

ok thanks, may be the pedal - since it was being used at the time, its the only variable there.

yes it does try to arc up - cuts out though due to the no gas, the water pump kicks in and the amps are going up and down on the display when you move the pedal.


I'm not sure if the system kicks in the water pump and the gas solenoid at the same time or if that is controlled by the foot pedal.


is it likely the solenoid could be fused and that would have burnt out?


thanks for your reply btw.

[awoo]

Sept 4, 2015 18:11:09 GMT 93fxdl said:

Had the opposite with a mig welder, the solenoid stuck open, giving constant gas flow, a few swift taps sorted it. Hope your fault is cured as easily.
Ttfn Glenn

thanks, I'm hoping the hand of god will sort it too. i gave the machine a few whacks but that didnt do anything. will be more direct tomorrow when i get back to it.

[skylinedave]

Well if its trying to arc up then its not your peddle , deffo the solenoid .Does it have H/F start up ?

[awoo]

yes it does have HF start up.

[skylinedave]

Is the hf working ? Is it making the same noise ? Does it try to arc up normally and furr up the tungsten because of no gas ?


Just trying to eliminate knackered hf as the problem ?


Second thoughts the gas should still work then .

[awoo]

yeah it ignites the arc but furs up the tungsten because of no gas.

i don't get that click and hiss of gas any more.

[awoo]

ok, narrowed it down to the solenoid.



i get gas to the machine from the regulator, so that rules the reg and bottle out.

i get voltage to the solenoid from the machine when the pedal is pressed - so it ought to trigger the solenoid. although the solenoid should work if i get continuity through it shouldnt it? as i get a continuity reading through the solenoid, i thought it may have burnt out and caused it to stop working but it appears not to be that.

pedal is ridiculously simple inside so wont be that, just a switch and potentiometer (why are they so expensive!?!).



i am thinking, with the above in mind that the solenoid is jammed, so this will be the next thing i look to fix before buying a replacement.

[skylinedave]

Yes I'm betting its jammed . And yes , as i stated , pedals are ridiculously simple inside , if nay thing goes wrong its usually a screw thats come loose !

[93fxdl]

Most solenoid valves are electromagnets, so test if there's a magnetic field around it when powered up.
Ttfn Glenn

[awoo]

ok, update, fixed...


it was kinda user error i have to admit.


the regulator was the problem here. when i pressed the pedal to purge the gas and it all stopped, the regulator needles juddered then went to full pressure on the second gauge. the pressure must have been so high against the solenoid that it couldnt open.


i bought my rig second hand, when i set it up i had trouble dialing in my flow rate, it was good enough although no knob twiddling made a difference.


i think the regulator had been set right and just left by the prior owner. my thinking is that it was stuck in position and i had the knob wound out enough to just let all the gas through, then something must have freed off the diaphragm and thats when it stuck.


i only figured it out when i tried the machine with no gas connected and the solenoid worked. each time i tried before i had the gas on so it would have been backing up against the solenoid and stopping it from working.



so moral of the story is i set it up wrong, panic set in and i'm an eejit


thanks for the help, it was a moral booster just having help here!

[skylinedave]

I would recommend getting a flow meter if you do not have one . You can then just crack the regulator open , hold the torch away from your work , press the pedal to get the gas going and see and adjust to what you want .

I will not work without one as its just pure guess work to how much is coming out otherwise .

[awoo]

it does have a flow meter, sorry thats what i meant to say, the flow meter was the bit at fault, it was wide open. got it dialed in now though, 8 Lpm