Arc Problems

John, Do the units have a spark gap set? (and/or clean contacts). Just a thought, may be a longshot but it's free to check. Give Miller a buzz and find out the spec for that model.

Hope it helps, Free fixes are my favorite,

Rob

Rob

I have already set the point gap, but thanks for the info. The gap on this machine is 0.3mm and I have tried all settings to no avail.

sounds like maybe the gas is being restricted. check that the gas flow doesn't drop off after starting.

Or there is a leak that is sucking in air. But on two machines??? What is common to them?

Tom

Along Sailors note, How about the plug to the foot pedal ? does it have one ? is there a pin loose or a bad pin or corroded ? A broken wire in the cable that comes and goes ?

Try a different foot pedal maybe. Is the gas pure ?

Mart> sounds like maybe the gas is being restricted. check that the gas flow

Presuming: machine is on AC, and the balance is set to a reasonable point, the material has been cleaned appropriately (stainless scratch brush), the current is set correctly.

Check the tungsten. It sounds like an inapropriate type. (sanity check: try pure with a balled end)

pooledst

system

Thank you all for your input.

I have today checked the gas and changed the bottle to another one.

I have also changed the tungstens to known good ones and still have the same problem.

I have also changed the footswitch and even operated the machine without a footswitch. I then changed the High Frequency points, reset the gap, replaced the High Frequency capacitor. As a last resort I changed the main rectifier on one of the machines. I still cannot solve this problem. I have now spoken to milller, and they are sending me a loan machine to try in their workshop. I will then remove one of their machines back to my workshop and test it there.

If any one has any further suggestions please let me know.

Good report. Wonder if the main AC at the plug end is faulty ? Or the connector where the cable attaches inside the unit. - e.g. the AC mains source verification. Perhaps a screw rattled loose or due to thermal stressing worked loose. Maybe under load the input voltage is the issue.

Martin

Please check your incoming voltage and make sure you have full voltage on all three phases when the load is applied. Then take a clipon reading on each leg when the output is shorted through an electrode in the stinger and in the ground clamp. ( I recommend using 1/8 rod with output setting of 80 amps) you will heat the rod up red hot but it should hold (if it is getting too hot dial it down). The input current should be the same on all phases and the voltage should dip evenly. If it isn't you may have one mains leg that has low ampacity ( bad breaker buss connection or connection in the panel or terminal block) or an internal contact failing or winding problem. Let us know what the test results are.

Pete