Millermatic 200 got HOT HOT HOT!!!

[Pipeliner]

A few years back in my unexplainable quest for the ever elusive MM200, I picked up a known DOA. Today, for reasons unknown, after years of stacking crap all over it and shoving it from one corner to the other, I decided to pop the covers and see where the magic smoke trail led me.



I'm going to take a stab at it and say the (missing) high range tap got loose and subsequently caused the meltdown or melt up. Anyone ever seen the likes of this?

[DougAustinTX]

Wow, maybe someone wired around the overheat/shutdown circuit?

[duaneb55]

I'd say you called that one correctly Pipeliner.


Have seen similar on a Bobcat reactor once.

[Pipeliner]

My gut told me it probably wasn't going to be good. It's a shame because everything else appears to be salvageable.

[duaneb55]

I'd think a good 'ol fashioned motor shop could rewind that but it might be a bit pricey though. An alternative could be part the rest of the unit out.

[Doug_]

Makes me want to go back and make sure I tightened my taps well enough.

I know that they can become loose from twisting the male plug just trying to got from High to Low range.


Are those some of the windings?

[Pipeliner]

I'd think a good 'ol fashioned motor shop could rewind that but it might be a bit pricey though. An alternative could be part the rest of the unit out.

I might check into it if I can find one and see how much for giggles.

Makes me want to go back and make sure I tightened my taps well enough.
I know that they can become loose from twisting the male plug just trying to got from High to Low range.
Are those some of the windings?

The red circle you made is the varnish coating that flaked off. But yes, definitely worth checking occasionally to make sure things are good and snug. Although, this is a severe case of neglect I believe. It was probably loose for a long while. The unfortunate part of the whole thing is that the jack plugs are CHEAP and EASY to replace compared to the damage done by using it "just one more time".....

[ccawgc]

Custom wound transformer can cost over $1000.00
My guess is a shorted diode and a stuck closed contactor.
welders up to serial number JA378747 did not have thermostats and the fan ran all the time.
After that they added fan on demand with thermostats in the transformer and on the diode heat sinks. Plus the diode heat sink has a second high temp shut down thermostat.
If your clever, You might be able to find a transformer from a newer welder and merry it to the old welder. A new transformer will be aluminum wound and might have a center tapped secondary. That way you only need two diodes instead of four. Just has to have a tapped primary.

[Pipeliner]

I think this is a JC prefix. I'd really like to find a good transformer.

[ccawgc]

The older transformer is obsolete, the newer one is not stocked. it will take a phone call to miller
to find out if it is obsolete or a made to order part with a 15 day lead time.
there is about 8 different transformers, will need serial number and primary voltage to get the right part number and see if there is any thing left at miller.

[vwguy3]

What about a used transformer?
May be a good chance one of the guys here has the right part from a parted machine.

[Pipeliner]

What about a used transformer?
May be a good chance one of the guys here has the right part from a parted machine.

That would be ideal.

[Doug_]

Pipeliner I don't know where you are located but if it's anywhere near EL Cajon California you might want to to look at this.

http://www.ebay.com/itm/Miller-Mille...item3f4e3fe33a

I do see what looks like the low tap for the transformer hanging out of the side in one photo.

[Pipeliner]

Thanks Doug, but too far. Nice looking machine though. I've made a few calls, but no dice on locating a transformer for mine. I'm not giving up yet.

[Cervantez]

I've seen MM's strapped incorrectly go up like this...Instead of being strapped for 208 or 230 or in some machines 230 - 460 they accidentally strapped it in the middle of both voltage range and went to town welding.

[7A749]

You may be able to find an older Spoolmate 200 and rob the transformer out of it. I believe they will be the same, or at least very similar. Being the machine is as popular as it is, finding a drop in replacement will be difficult.

I won't even tell you to waste your time with some of the rental guys who have stockpiles of busted stuff.

Some of them like to lead you on impossibly long goose chases after telling you they have the parts you need.

BTDT. Find a Spoolmate 200. That's your bet bet from where I'm sitting.

IMHO of course

[Iain P]

Maybe I'm just crazy but I'd consider winding it myself if I were you.

[Pipeliner]

I've seen MM's strapped incorrectly go up like this...Instead of being strapped for 208 or 230 or in some machines 230 - 460 they accidentally strapped it in the middle of both voltage range and went to town welding.

I didn't even look at that. Knowing where it came from, it should have been operating on 220.

Some of them like to lead you on impossibly long goose chases after telling you they have the parts you need.

BTDT. Find a Spoolmate 200. That's your bet bet from where I'm sitting.

I hear ya on the goose chasing. I'll keep my eyes peeled for the Spoolmate option.

Maybe I'm just crazy but I'd consider winding it myself if I were you.

I haven't the slightest how or where to start that process. But if all else fails I suppose it's pooched any way, how much worse could it get?

[Pipeliner]

Maybe I'm just crazy but I'd consider winding it myself if I were you.

I'm really considering tearing into this transformer. Is the old copper junk or can it be revarnished and reused?

[Iain P]

I'm really considering tearing into this transformer. Is the old copper junk or can it be revarnished and reused?

Here's what I would do: disconnect every thing from the secondary winding. Then check it with an ohm meter to make sure the wire didn't melt clean apart anywhere (should get a really low resistance reading close to 0). If that check out gently move the wires so they are evenly spaced out again since they seem to have gotten moved up to the top somehow. With the turns of wire spaced back out but not connected to anything disconnect the fan and fire the thing up. Squeeze the trigger and listen for any load buzzing from the transformer. Slightly noisy humming is expected but loud buzzing means one or more turns are shorted. If the transformer sounds "ok" let it hum for maybe 30-40 sec. Turn the thing off and unplug it. Carefully feel the windings to see if the transformer is hot. If you can hold your hand on it congratulations there is life left in that transformer! Now all you have to do is go the the hardware store and buy shellack and a cheap brush. Brush on 3 heavy coats of shellack working it in between the windings. Let it dry 24 hours in between each coat and let it dry a week before trying it out. Once it's dry hook it all back up, fixing whatever caused it to do that in the first place, and enjoy.

That should do it because the more I look at the picture the more I think it looks worse that it is. If it fails the above tests of buzzing and heat, we can get into full blown rewinding.

[rhunt]

IainP gives sound advice!! Do as he says and all should be well in the land. IainP, you must have worked in a motor or transformer shop at one time. Best regards Bob

[Iain P]

IainP gives sound advice!! Do as he says and all should be well in the land. IainP, you must have worked in a motor or transformer shop at one time. Best regards Bob

Thanks! I've may have rebuilt a motor or two. This was my winter project: http://weldingweb.com/vbb/showthread.php...Cutter-Rebuild

[Pipeliner]

If that check out gently move the wires so they are evenly spaced out again since they seem to have gotten moved up to the top somehow.

Once it's dry hook it all back up, fixing whatever caused it to do that in the first place, and enjoy.

That should do it because the more I look at the picture the more I think it looks worse that it is. If it fails the above tests of buzzing and heat, we can get into full blown rewinding.

I think the wire grew up to the top like a reverse slinky because it was so hot. This is how I got it, so I'm not exactly sure what the original issue was. However, the high range tap (on the front panel) is missing. I can only assume it got loose and came in contact with the case (frame) and someone just kept giving it the business until poof.

[Pipeliner]

I didn't unhook anything yet, but the wire moved back down really easy. Problem is that it won't stay spaced apart; it just falls down on itself. I'm thinking I may need to cut the transformer loose from the frame so I can brush the crusty stuff off and work it back around so it's snug.

But before I get ahead of myself I need to disconnect and check the winding.