Miller Dialarc

[Jorville]

I bought a Miller Dialarc HFP new back in 1980. the cooling fan started to make noise after 30 minutes of run time, I called Miller and they said the warranty had expired. The machine had sat on it's shipping skids for a year before I got it wired up so I was SOL. After the fan noise it has sat on it's shipping skids for 35 years or so. Couple of weeks ago I wired it up and the motor still makes noise after a bearing house told me the bearings were good. Turns out the motor housing was machined .006 thousands too much. I fixed that with shim stock.

The machine seems to arc weld fine, I did not do much, I want the TIG capability. I feel there is something wrong with the high frequency. With both switches in the correct position, gas turned on and gas at the torch, the foot pedal pressed down, there is no high frequency start. I have to scratch start the arc. and when I do the tungsten burns back, and if I press the pedal down further the tungsten burns back faster.. I am tempted to have a service tech come out and take a look at it. You guys have any thoughts or ideas on what might be the problem. This machine has sat in a un-heated building for the last 35 years, would the cold wreck electrical parts of the machine?

 

[Mysfyt]

I would start by cleaning my points and then setting the gap. The image shows what they look like. I think they are on the R side of the welder as you are looking at it, but I'm not sure. Clean with some fine emery cloth and set the gap to .015".

The image shows the lower left point missing, BTW.

 

[Oldtink]

Here is the op manual if needed. Tungsten burning off? Sure you have sufficient gas flow at the torch and no leaks?
https://www.millerwelds.com/files/owners-manuals/O315_MIL.pdf

 

[Mysfyt]

I stand corrected. After reading through the manual, the points are under the front panel and the recommended gap is .008"

 

[Jorville]

Thanks Mystyt, I will look at that. I don't know what makes these thing work. When they are new it is magic. I can see where there could be some corrosion.

 

[Jorville]

Oldtink, I thought of that also. I have turned the machine at work on and started the arc and burned off some tungsten and said woops, no gas. This thing won,t even start the arc on the start position. The gas flow is at 25 and inside a building. After pre flow there should be Argon.

 

[Jorville]

Mysfyt, You were right on. The machine sat for so long the points were all corroded up. I took the point holder off the machine and cleaned out the bores the points are in and cleaned up the points. I have high frequency now. I still have a problem with the tungsten burning back though. I might have a bad flow meter I see when I push the pedal down the flow is 20 (a little high I think) then the flow drops to nothing or a little of nothing,

 

[CalG]

polarity correct?

dc Rev will ball up an electrode in a big hurry.

 

[Jorville]

polarity correct?

dc Rev will ball up an electrode in a big hurry.

I have it set for DC straight and the tungsten just burns back. Now I am seeing the gas flow go down to zero or very low. I have to find out why.

 

[CalG]

shove the torch on a plastic pail of water, and watch the gas flow as bubbles.
Be careful of what might be touching, There is welding current there too. ;-)
Stuck diaphragm in the regulator? Is the gas rig 35 years old and never been used? NOT GOOD!

Just a point.

As far as diagnostics over the internet goes. There is a HUGE difference between a tungsten that "burns back", and one that "burns black".