Problem with Square Wave TIG 255

[Old Rod]

I am having a problem with a used Square wave TIG 255 that I bought. I thought one you with more experience would have seen this before, or could point me in the right direction.
I believe that the high frequency portion of the welder is working because I am able to hold the electrode at the correct distance from the material, and the arc will start. However, the arc does not have the ability to form a puddle. Welding 1/8 inch mild steel, I set the machine at 160 amps before I start to weld, and as soon as I depress the foot control to start welding the display shows the amps dropping to zero and the volts go between 27 and 30. The arc is so weak the auto lens on my helment turns on and off. This is the settings I used for the 1/8 inch steel:

Welding in: DC-
Weld Mode: TIG 2-step
Current Control: Remote
High Frequency: Start only
Wave Balance: Off
TIG Pulser: On
Amps: 160
Tungsten: 3/32, 2 % Thoriated
Gas: Argon


I also tried to weld some 1/16 aluminun sheet in AC with the following settings and had the same result.

Welding in: AC
Weld Mode: TIG 2-step
Current Control: Remote
High Frequency: Continuos
Wave Balance: Auto
TIG Pulser: On
Amps: 70
Tungsten: 1/16, pure
Gas: Argon

I don't think it is generating the amps to kick in after the high frequency starts, and melt the material.

Any help or advice is greatly appreciated.

Thanks
Old Rod

[old fart]

It sounds like the powercable in your torch is broken. HF can get through but not welding current. Try another torch or if you have a multimeter check the cable resistance it should be less than 1 ohm. Oh by the way the ground clamp is connected ?
O.F.

[Old Rod]

I will get the voltmeter out and take a look at the resistance in the torch. I did have the ground cable connected, but it never hurts to make sure when diagnosing what could be a simple problem. I will let you know how the ohms test goes.

Thank you for the input Old Fart.

[Old Rod]

I checked the torch with the multimeter, and there was no resitance in the torch. After zeroing out the multimeter, I got a reading of 0 to .1 Ohms on the torch. It does not appear to be broken or internally shorted.

Any other ideas?

Thanks

[SundownIII]

Old Rod,

Check to make sure your work (ground) clamp is secure and near where you're trying to weld.

Attach a set of stick leads and try stick welding with the machine. If nothing, then I suspect it's time to contact your LWS for a recommendation for a service facility.

[Roger]

I checked the torch with the multimeter, and there was no resitance in the torch. After zeroing out the multimeter, I got a reading of 0 to .1 Ohms on the torch. It does not appear to be broken or internally shorted.

Thanks

This only means no resistance to mili-amp loads. One of the leads could still have bad connection or partially broken conductor that would cause voltage drop under normal welding load. If problem was in ground lead could be caused by poor clamp to work connection or if partial broken lead could feel hot spot in problem area of lead. Voltage reading at welder lead connection and at end of leads both under load with big difference would indicate problem.

[Old Rod]

SundownIII,

I have worked with the ground cable and made sure it had good connection and was close to the welding area. This did not change the abitlity to start form a puddle, same as original post.

I switched to stick mode, and was able to weld in DC+ and DC- with no issue. The amp reading on the display fluctuated around the 132 amp setting I was welding at. No issues in stick mode.

Thanks for the tips , any ideas with it working in stick and not in TIG even though high frequency seem to be working?


ROGER,

I understand your comment about not handling full amps at welding load for the torch cable. I do not have another torch, but will try to borrow a known working one or go buy one. The ground cable and clamp are new, and should not be the problem, but I will verify.

Thanks for you help.


Old Rod

[SundownIII]

Old Rod,

Your results with stick welding would lead me to believe the problem is in the torch, not the machine itself.

If you were near VA, I've got a couple spare torches you'd be welcome to try. TX is a ways to go though. Check with your LWS. They may let you borrow a used torch to try.

Swap out that torch and I think things will be OK.

[Craig in Denver]

Maybe try it with the TIG Pulser: Off.

[B_C]

Yeah good point...because we don't know where the PULSER is set .......Still think it's the torch though...

[out in the shop]

i have the same machine, if you can weld stick you should be able to weld tig. so you think your h/f is working, turn it off completely and try a scratch start. if you cant scratch start, i would guess you have cabling issues
also....i dont really understand the whole electronics thing BUT on the slim chance you have a bad foot pedal try this
switch over to TIG FOUR STEP
turn your machine to 150a
hit the pedal ONCE AND LET OFF COMPLETELY
this will start a ramp up to 150 amps , to discontinue arc, fully press down on pedal and ramp back.....
also another question????? what gas do you have? if you dont have the right gas you wont be able to establish an arc through! good luck todd

[Old Rod]

Thanks for the help guys.

I was able to scratch start in TIG mode so I am planning to get a new torch. I talked with the LWS guy and he suggested switching from my 25 foot torch cable to a 12 or 15 foot. I will be getting one a soon as they re-open on Monday.

I using Argon gas, and will try the 4 step mentod you suggested, Out in the Shop.

I will also turn the TIG Pulser off.

I will let you know how it goes with the new torch.

Have a Merry Christmas guys.

Old "torchless" Rod

[out in the shop]

1st if you were able to scratch start , i dont think its cabling (sorry). also i think youll really regret going to a 12 ft torch. i had a 12, i now have a 25 and wish i had longer. dc doesnt really care about the lenth of the leads,(to an extent) but the longer the leads on hf the more there is a chance to bleed off the hf. but this is insignificant in 12 or 25 ft . i do hope it is the torch for your sake. keep us up to speed. if in fact you need to pay someone to open it up and repair it. it is well worth the money. you have a very respected welding machine. that has enuff bells and whistles, plenty of power, great welding charactoristics the only downside to it (AS WITH ANY TRANNY MACHINE) the power company is gonna love you.
good luck todd

[Jeffw5555]

Have you purged all of the air out of the torch? Do you have Argon flowing before and during arc initiation?

If you haven't got all the air out of the lines and/or don't have Argon flowing out the torch, you will not be able to establish an arc. (a good one, anyway)

Jeff

[B_C]

That would SMOKE the TUNGSTEN instantly...so that can't be the problem.....