Possible trouble with Miller 150s, need opinions

[powerplant]

I recently purchased a used Miller Maxstar 150s. I also purchased a air cooled tig torch with a gas valve. I have hooked the power lead to the negative pole and the ground to the positive pole to achieve reversed polarity (I think that is right). I am running between 15-20psi of argon for sheilding gas.

The problem: I can be welding along and all of a sudden the arc will stop for no apparent reason. I can then reach down and scratch start it again and it will start up again... maybe run for awhile or just a little bit and stop again. My 220 supply has a 40 amp breaker and I know it is not tripping that... is there something inside the machine that is causing the arc to stop? I know there is a built in over temp device but I had someone watch that while I was welding and it never came on.

Also... I tried to get down in the 10-15 amp range to weld some sheet metal... sometimes the arc seams hot and sometimes the arc will not even start a puddle. ( I think I figured this out though... I needed to scratch start it a couple of times to get the arc established)

Is it a problem with the machine? I don't think it is my welding style as I am keeping the tungsten about 1/8 inch or a little less away from the material.

What gives?

[6010]

I can't help you out on the welder but there are a couple of things I can tell you.

I

have hooked the power lead to the negative pole and the ground to the positive pole to achieve reversed polarity (I think that is right).

1. Your polarity is correct . electrode should be negative. work lead or ground positive - but it is called straight polarity.

I am running between 15-20psi of argon for sheilding gas.

2. Your gas flow looks like it is correct if it is set on 20 but I think you mean 20 cubic feet per hour CFH not psi.


I would turn up the amps and see if that helps.
With no more experience than I have that is all I can help you with but I am sure someone with more experience on this board can help you out further.

[Synchroman]

I recently purchased a used Miller Maxstar 150s. I also purchased a air cooled tig torch with a gas valve. I have hooked the power lead to the negative pole and the ground to the positive pole to achieve reversed polarity (I think that is right). I am running between 15-20psi of argon for sheilding gas.

The problem: I can be welding along and all of a sudden the arc will stop for no apparent reason. I can then reach down and scratch start it again and it will start up again... maybe run for awhile or just a little bit and stop again. My 220 supply has a 40 amp breaker and I know it is not tripping that... is there something inside the machine that is causing the arc to stop? I know there is a built in over temp device but I had someone watch that while I was welding and it never came on.

Also... I tried to get down in the 10-15 amp range to weld some sheet metal... sometimes the arc seams hot and sometimes the arc will not even start a puddle. ( I think I figured this out though... I needed to scratch start it a couple of times to get the arc established)

Is it a problem with the machine? I don't think it is my welding style as I am keeping the tungsten about 1/8 inch or a little less away from the material.

What gives?

Does the "S" model have High Frequency start? I looked at the Miller Products list and it shows that only the "STH" model has the HF.....if no HF, that could be one explanation.

If indeed it has HF start, then I would suspect dirty points in the HF generator unit.
My 2 cents.......


P.S. I just looked at the manuals and it appears that your machine doesn't have HF. That would limit you to scratch start and would cause some interruption of welding if you reach a different quality of metal or if the tip moves too far away from the metal...assuming that I read the manual correctly...it's a slow day and I don't have anything to do right now. LOL

[powerplant]

I don't think it has high freq either. This may be the answer to the one problem I am having trying to get the arc started at very low amps.

I was messing around with it again today. Ran a bunch of stick with no problems. I then went back to tig.... after talking with some people on the motorsports forum I started to suspect my flowmeter. I have a ball type and I had it tipped at a 45 degree angle so my bottle would fit under a shelf in my garage. I straightened that up and now it seams to run fine. Another thought is I may not have had the valve on the torch body open fully either.

For now it seams to be working... hopefully this doesn't return.