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miller welder transformer 188061 replacement

buckhunter

Plastic
Joined
Mar 4, 2019
Hello,
Wondering if anyone here may have had to replace the Arc start pulse transformer in their welder?
The welder I am trying to repair is a mac tools TigW150/230V
The transformer part # 188061 has burnt out,,,,, visibly burnt out..
They want almost $1000cdn for the part.
Its gotta be a $30 transformer, small, very light. I found a guy on youtube who re wound his own with great success, but didn't really give any specs on input and output.
Would like to goto Sayal or newark and see if I can find one close to try, but I need to know the specs, which are not given out by Miller, or by the manufacturer Cramer, as the transformer was custom made for miller, the part number only refers to the miller transformer.

I think im looking for something with 120V input, 5000V output, so far, its a rare bird.

THANKS muchly for any help.

miller-188061-hv__96160.jpg
 
Only two leads, or are the others not shown in the photo? The two shown are NOT high-voltage wires or connectors, and it isn't a transformer if there are only two wires.
 
Its difficult to get 5kv out of a transformer that small which makes me think if they do, its a high frequency pulse discharge. Not a 5kvac 60hz output which would require about 50,000 turns of wire on a 30va core transformer.

The smallest microwave oven transformer you can get your hands on is around 120v:1800 turns ratio. It may work.

The photos appear to show 3 wires.

Need a lot more info. Particularly with regard to why it burned out.
 
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The manual shows T2 is a 2 coil transformer with capacitor in series, across the output. It obviously provides the hf start.

If the capacitor fails shorted, the transformer would burn up.
 
There are two spade connections on the other side exiting the top of the coil,
I was able to determine today that it is a HF HV impulse transformer to start the arc, And I also learned to check the capacitor, as Johansen has mentioned, thank you.

That is the $1000 part on ifexport Ron.
Another retailer, similar price : https://weldfabulous.com/miller-188061-xfmr-impulse-hv/

I took a pic of the wire diagram on the cover of the welder, I only got part of it tho, poor camera skills.
Its labled T2 on the diagram but I was not able to find any specifications on it. Dont have a manual.
Theres a fella did a you tube video and made his own, beyond my skills im afaid, But he says he did 10 windings on the primary, and 660 on the secondary, and got a good bead on aluminum.
He mentioned 65v on the primary, and 5200v on the secondary, but did not show readings, I think it was just his math. And the welder model he had was slightly different.

Sorry, thats all a bit over my head, was just hoping it would give me a clue where to start to look for a close replacement.

Ill check the capacitor, and see if I can find a replacement, and a small microwave to tear into.

As per the diagram, could I turn it on, and just check the voltage across RC2-1 and RC3-1 Leads 51 and 52 with a voltmeter? That would tell me the input voltage at least.

Thanks for the reply's, appreciate your time.

IMG_8620.jpeg
 
Hello,
Wondering if anyone here may have had to replace the Arc start pulse transformer in their welder?
The welder I am trying to repair is a mac tools TigW150/230V
The transformer part # 188061 has burnt out,,,,, visibly burnt out..
They want almost $1000cdn for the part.
Its gotta be a $30 transformer, small, very light. I found a guy on youtube who re wound his own with great success, but didn't really give any specs on input and output.
Would like to goto Sayal or newark and see if I can find one close to try, but I need to know the specs, which are not given out by Miller, or by the manufacturer Cramer, as the transformer was custom made for miller, the part number only refers to the miller transformer.

I think im looking for something with 120V input, 5000V output, so far, its a rare bird.

THANKS muchly for any help.

View attachment 411377
As Gordon mentions, that is not a HV ignition transformer, or a transformer of any kind, it's an inductor of some kind.

Can you provide a photo of the actual failed unit? And, does the welder come with a schematic? I do see an online schematic. Which component is it that failed?
 
Find the model # of the similar miller model and download the manual for it. Your likely to find a better schematic and information that way. Then that could open the door to other distributors and service shops that you may be able to get a better price and availability from.
 
T2 on the diagram is definitely a transformer, with two windings on one common core. Confirmed by referencing connections RC2-1 and RC3-1 which are on wires numbered 51 and 52.

Some may be confusing T2 with Z2. Z2 is an inductor.
 
I have 70 pounds of 24 awg wire that has a thermal resin on it that can bake into a monolithic coil, that i paid 4$ a pound for, if 660 to 10 turns on a 30va core can work for you, i can take the time to build one that can handle 5kv, might have a friend 3d print a segmented bobbin. Or do it the old way with layers of paper.

However, you may find that a 240:24v hvac control transformer, cut out most of the 24v winding so its more like 3 volts, drop it in a bucket of oil.. may hold up fine.

I tend to doubt the inductance of the transformer resonates with C1 in series with Z2, but you never know.
So Some experimentation may be in order, and we dont know the ratio of 10 to 660 except from what that other guy told you ... and it is difficult to measure 6kv at high frequency which is why his reading of 65vac on thr primary and 5kv on the output doesn't match his turns ratio.

It may be that any transformer that does not break down will work. A microwave oven transformer which can easily handle 6kvac (disconnect the secondary from the iron core, one end by default is grounded) is the first thing i would try. If it does not work, get it warm and tap out the magnetic shunts with a punch. If it still doesnt work, cut half the primary coil out (most of them are aluminum, so you really only need a chisel) to increase the turns ratio.
 
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I think the capacitor is mostly to keep DC out of the HV coil...... That could partly (or completely) saturate the core of the transformer and screw up transformer action.
 
The purpose of this transformer is to induce a high frequency sparc prior to the electrode touching the work.
Once the sparc starts, the electrode takes over and provides the power to weld.

Suppose as a last resort, I could try boiling this transformer and counting the windings.
Get a new bobbin, and coated wire and try a re wind myself,,, dont see that going to well honestly..

From what I have read regarding high frequency transformers, I prob should try and replace it with a similar built one, if I am to expect it to last any time,, But maybe that could be just sales hype?

Interested in trying the microwave hack if I can find time.
Im going to try contacting Cramer and see if they can send me specs, or maybe an alternative.
But Im guessing this was a proprietary model made just for miller, and they might be reluctant to divulge the specs.

Below is a pic of the capacitor, and also how it is wired to the electrode, The two connectors in my hand got the spade connectors on the back of the transformer and the two wires on the transformer goto the circuit board.

Thanks again for the advise.

IMG_8633.jpegIMG_8631.jpeg
 
it is unlikely that capacitor failed shorted, but test it anyways.
The core of your transformer appears to be ferrite. you can buy large ferrite cores and bobbins off ebay for not super cheap any more.

Heat the transformer up (boiling water will probably work), pull it apart, count the turns and the size of wire.
 
Capacitor is pretty large and low voltage for a straight transformer at that voltage, but I see no regular gap in the core, so it may be one. I assume the capacitor just shorts the secondary if you dip the electrode, and does not see the high voltage.

If it had a gap, I would suspect it of being a "flyback transformer" (a form of inductor, actually), which would mean the turns ratio would not be a direct factor in the voltage. More like an ignition coil, which is a form of "flyback transformer".

Still could be that, depending on the "mix" of ferrite (or iron powder) used in the core. Some "mixes" have an inherent gap to them. And a gap may be only a few thou, not very visible.

Transformers are a bit more complex when used in high frequency circuits. A grand is a bit steep for that one, though. Must be rather rare, or may be special order (made when and if any sucker orders one), if the unit is "that old".
 
Cramer Magnetics is still in business, it might be worth checking with their tech support, they might have an off the shelf replacement available.

It is much more likely the designers used an off the shelf part rather than a custom transformer for the design. It's not really cost effective if you're not selling millions. Whether it's still on the shelf is another question ...
 
If you are selling hundreds of units, you can get a custom unit. At the music company, we rarely used a stock part, because we needed different performance.

It was very cost-effective, because we could not buy what we wanted, and it was cheap enough to get custom. When you get into high frequency transformers, almost all of it is custom, other than certain stock gate drive transformers, and small stuff for common voltages.

That one is almost certainly custom. The makers jammed a wood shim into it to allow it to fit into a standard mounting strap of a type usually used for laminated core transformers.

If it was stock, there would almost surely be a standard mount means for that core.
 
Want to say thanks to everyone for the input, I was able to source a used unit from a member off this forum.
The item was shipped quick, was as described, worked perfectly.
Saved a great little welder from the scrap heap.

Thanks muchly,
Take Care...
 








 
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