keep melting tungsten out dont know why

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i have a l-tec heliarc 250 on ac with the hf on continuous  im using 2percent  lanthanated and it balls up instantly the tungsten then melts out up into the cone i've varyed the balance from max clean to max pen and every spot inbetween it doesent matter still does the same thing on dcen with 2 % thor it will ball right up right away but it wont melt out as bad but the arc wanders real bad any help would be awsome
Reply:Sure it's not on Dc+ ?
Reply:Would this mean he has a bad diode or something similar?Dave J.Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~ Syncro 350Invertec v250-sThermal Arc 161 and 300MM210DialarcTried being normal once, didn't take....I think it was a Tuesday.
Reply:do you have the manual? if not you can down load it from ESAB. Go to ESABNA.COMSupport, down loads, look for the manual F-14-316C in the old archives.Turn HF off and make sure it is off. Start out in DC+ measure with voltmeter. Switch to DC- and measure again, see if polarity changes. Switch to AC and retest. Try measuring all three settings for both AC and DC and compare. This will help you make sure the knob is on the switch correctly.You are looking for the DC polarity and AC value of each setting.If switch is correct, you may have a SCR that is bad or not firing right or a loose connection.
Reply:yea i have the manual in pdf form ...........when i turn it off to make sure its off there would be no arcing between the hf points right? and for the volt meter i can just put that on the work lead and ground clamp to test right?
Reply:1) Have you ever successfully GTA welded on AC before with this setup, or at all?2) What amperage are you set at?3) What diameter electrode are you using?Visit Tensaiteki.com
Reply:What gas are you using?
Reply:yes i have successfully welded in ac before though it was not on this machine it was on a newer miller inverter machine but i never had any of these issues with that machine ........im using 3/32 and my work peice is 1/8  and im using pure argon i thought maybe i had bad gas so i swaped the bottle with my buddys and same results so i know its not gas and i know its not the tungsten cuz were using outa the same box and its workin fine for him....also i dont know if this has anything to do with melting out the tungsten but the torch stays live just enough juice to make a spark but not enough to hold an arc i unhitched the pedal thinking that it was stuck or misadjusted and was causing this but with the pedal off it still had that lil bit of juice to the torch
Reply:i put my multi meter on it and on dcsp i had -40 dc volt and on and dcrp i have +40 dc volts and on ac i had 82 ac volts  i put my multi meter back on ac and tested the machine in dcsp and dcrp and had 90 ac volts on both acording to my multimeter dont know what any of this means but any help is greatly appreciated thanks guys
Reply:Do you hear gas coming out of the nozzle when triggered?
Reply:you can hear it and if you put your hand infront of the cone you can feel it
Reply:I had exactly the same issues as you. Massive burn back on the tungsten. I solved it like this:1) Hook up your tig torch to a air compressor and regulate it to about 10psi or so. Block the end and use buble water to check for leaks. My original torch had leaks, and was responsible for the majority of my troubles.2) I'm using 2% thoriated (Lanthanated should be even better). I found that at even at moderate amps that it was better to use a 1/8 tungsten rather than a 3/32. I was giving it too much heat initially for the 3/32 to stand up. I think the cup is a #7...it is large for the 1/8 gas fitting on the end of the torch, then tapers down to something a little smaller than 1/2 inch.3) Get used to where to bring in the pedal. Initially I used a lot of pedal, but after getting a feel for the setup, I use about 60-70% of the pedal and the puddle development time is good, without overdriving the tungsten.4) Make SURE your hf is working properly. Put your AC meter across the ac output, then turn on the hf. Does the ac voltage go up? From my experience it should. I used a 'scope to check it, but if you don't have one that should give you some indication5) On AC, check for DC volts. There should be very little (Less than a volt). If you have more than 1 volt, your rectifier may be dead, or you may be missing one leg on your AC feed. I had a loose connection on the main ac, and with how my old transformer unit works, this means I intermittently dropped one half of my AC output...very inconsistent and frustrating!!!! Also, you can check for AC volts on DC mode. There will be some due to ripple, but it will be comparatively low compared with the DC voltage. These measurements are done at no load. Be careful. These voltages are in the range that can hurt/kill you.Hope that helps.Chay
Reply:When you stop welding does your tungsten stay shiny clean?DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:yea i have 0 dc volts in ac so from what you say thats good but i did have ac volts on dc almost double od ac volts to the dc volts but idk like i said my torch stays live just a lil bit so idk if that has any thing to do with it and i ruled out the pedals so something inside is keepin the torch live and idk what yet but thanks and first thing i will deff check for leaks up to the torch and the torch
Reply:Originally Posted by deutzmani put my multi meter on it and on dcsp i had -40 dc volt and on and dcrp i have +40 dc volts and on ac i had 82 ac volts  i put my multi meter back on ac and tested the machine in dcsp and dcrp and had 90 ac volts on both acording to my multimeter dont know what any of this means but any help is greatly appreciated thanks guys
Reply:its just a cheapo meter i usually lose them to fast to justify buying a expensive meter it can hold a dc arc ok but it will wick the metal up on the tung as soon and it makes a puddle and im not dipping it in the puddle it actually wicks right up onto the tungsten but even contaminated with some patience you can still continue to weld in dc just pisses me off more than anything that i dont know how to fix it yetim located in janesville WI
Reply:You need to hold a bigger gap.  About the size of the electrode.DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:i wish it was just me not having enough gap but as it is i hold it a 1/8 to 1/4 out to try to keep it from wicking up on the electrode but it ether wicks up on it or breaks the arc
Reply:Originally Posted by deutzmani wish it was just me not having enough gap but as it is i hold it a 1/8 to 1/4 out to try to keep it from wicking up on the electrode but it ether wicks up on it or breaks the arc