Still have a problem with Miller XMT-300 and S52

[TubularFab]

I had posted a little while back about trouble I was having with a Miller XMT - 300 CC/CV inverter connected to a Miller S-52E wire feeder. It would weld fine for a couple of inches then start welding like crap for about 1/2 inch before suddenly welding fine again. When it acts up it seems like either the wire feed is way too fast or the welder significantly drops it's output - the wire starts pushing the gun back and the weld gets real cold and globby. I thought I'd fixed the problem when I found a grossly oversized liner was in the lead and changed it out for the right size one.

But, today it was doing it again. It welds great for a couple inches then acts up for 1/2 inch in a fairly but not completely regular cycle. I cannot see anything obvious causing it. The feeder runs smoothly at any speed when not welding. The rollers, liner, wire, and contact tip are all new. And, if anything the wire is speeding up so I doubt it's any of those. Actually, I doubt it's speeding up as well - I think I'm loosing my current.

Anyone have any ideas to try and diagnose this further? What am I missing??

Oh yeah, gun is positive, ground negative. Using 75/25 argon CO2.

Thank you,
Jason

[Joe H]

I remember one of the MIG weldors at work having a problem like this. It turned out to be gas regulator. It seems it would work OK for a second or two then stop delivering gas, then start working again, etc...

[MAC702]

How old is the machine? Have you called Miller's tech support? 1-800-4-A-MILLER. You will find them quite helpful.

[TubularFab]

The inverter is probably late 90's, the feeder is maybe 80's? Neither would be under warranty...

A welder I work with just gave me a bit of a clue. He said in the past he had heard of mig welders doing weird things when around other electrical equipment of strong electrical/magnetic fields. In those cases he said the actual arc would jump to something else rather than go through the wire.

I do not have anything electrical or magnetic around my welder, but there is an odd thing that occurs along with the drop in current. There is a yellow arc flash at the same time. Do you think the arc is jumping to the nozzle and then to the part I'm welding or something weird along those lines? I don't think I'm loosing sheilding gas because the weld itself doesn't get all porus and nasty. Plus, I had a bit of trouble with a breeze through the shop yesterday and it did cause all the normal loss of sheilding gas problems. Also, I'm towards the end of a bottle that worked fine on my other welder and using the same regulator as well.

Thank you,
Jason

[TubularFab]

Ok, to add to my confusion I went to my shop over lunchbreak and burned about 6 feet of weld on some scrap without a single bit of it acting up! Doh! I hate intermittent issues!

I am wondering if I'm seeing a voltage drop on my power supplying my shop? Another thing is I am running it on a 75' extension cord made of 8 gauge wire, so that isn't helping. I guess I need to wait till it starts acting up again and try running without the extension cord... Incidentally, I was not running at very high amperage yesterday - something like 100 amps, so I wasn't worried about the cord too much...

[MicroZone]

I would take it off the extension. Make sure you have good clean work and a good ground.

[MAC702]

The inverter is probably late 90's, the feeder is maybe 80's? Neither would be under warranty...
A unit does NOT have to be under warranty to get help from Miller's tech support hotline. It has to be under warranty to get the parts and labor to fix it for free. Try calling Miller first.

[WHughes]

Could be a power issue in your building. There are areas in my building that cause the xmt or alt304 to act up. Also, I assume the wire feeder is the correct voltage? Some millers run on 12 and some on 110. We have both in our shop although I don't think thats your problem, it couldn't hurt to toss that out there just in case.
Good luck
Bill

[TubularFab]

Ok, after welding fine for a couple of projects without any acting up over the last week it was dead today when I tried to use it. The unit powered up ok and the feeder and gas valve all worked, but it wouldn't put out any current. The amp/volts display would go from the set number to either -.04 amps or .0 volts. So, it was acting like it was trying to output current, but wasn't.

So, for grins I fed out some wire and let the end of it sit on the welding bench. I switched the contactor switch to ON and let it sit whiel I did some other things. About 5 minutes later there was a pop as the wire suddenly heated up and melted off. Now the welder was putting out current and working normally. I shut it off for a while, and when I powered it back up no current again.

So, what goes bad in an inverter power supply when it acts up like this?

[MAC702]

Miller would probably know. Seems like you're doing everything except ask THEM. I'm not trying to be a jerk, I just don't understand why you haven't tried calling the company, which has a reputation for customer service and staffing technicians who can answer most questions over the phone, especially since we haven't been any help yet.

[MicroZone]

I would definately CALL MILLER. I bought a TIG welder 2nd hand and they had the manual to me in a few days. Their customer service is EXCELLENT.

MILLER Phone: 920-734-9821

[TubularFab]

Well, I finally had this great idea all on my own to call Miller's tech line. I was resisting just based on all the other experiences I've had calling tech support lines for big companies; they universally suck! But, I was amazed by Miller's! I was immediately patched through to a tech guy who was very knowledgable and helpful and was not even put on hold! No giving all your information to some idiot who then decides if you are worthy of tier 2 tech support! No getting someobody in India who has only mastered the phrase "thank you kindly, please turn off your Dell computer and restart it" and knows no other English. (Not knocking anyone from India; only saying out of country tech support is a bad idea!)

But anyway, Miller's help line was very impressive! He gave me a couple of things to try, but unfortunately it looks like the $600 main circuit board has a problem. He even suggested I tried having mine repaired by an outside company rather than buying a new board from them. I found a couple of companies that do that, looks like about $130 - $200 that route.

Boy am I glad I thought about calling thier tech support all on my own!
Jason

[MicroZone]

Ya, good thing.....hahahaaaa.

[dandp]

My main board on my XMT 300 has gone south also. Who did you find to repair your PC-1?

[99blackzr2]

My main board on my XMT 300 has gone south also. Who did you find to repair your PC-1?most of the miller inverter welders at my college are having the same problem with the main boards going bad.they are slowly replacing them with lincoln inverter welders.must be a common problem.

[TubularFab]

Well, just to update this post. After Miller decided the main board was definitely bad I found a place not too far away that rebuilds and guarantees the board for 90 days for $167. So, I tried the welder one last time before sending it off, and it definitely was still acting up. It was 10 minute from the time I turned it on until it would output current, and then it was still intermittant.

So, I sent it off for what was supposed to be a 2 week turnaround. A month and a half later they told me they ran the board on a test rig for 6 hours and found nothing wrong. $167 + shipping later and I have my board back with nothing done to it but it does carry a warranty now!

I plugging it in, and the welder runs fine now. So, did their 6 hour run dry out some moisture in a capacitor on the board? I wiggled all the connections and reinstalled the board once before sending it off, and the problem never went away. Weird!

I'm not sure I'd recommend the shop that repaired it - they were very slow, and totally unprofessional about they way they handled it. They told me three times they'd call when it was done and get a credit card number for the billing. The last time I talked to them they said they would hold off the billing until we figured out what was going on with the welder. I am never at my shop when UPS comes by, so I wanted to be sure it didn't come COD. Sure enough, it did and I was not able to meet up with the ups guy (another long story). So, it took a lot longer to get it back.

Jason

[MicroZone]

That is terrible Jason. I'm having similar run around with my plasma TV but I am trying to fix it myself. Looks to me just that the 250v capacitor is bad, so I've been running around trying to find local suppliers that carry them. Went to one that said he had a 250v/560uf and they sold my gf a TALL 350V/560uf. No way it would fit in the back. Finally found one online for $3.97 plus ship. The TV place wanted $150 to repair the board. :laugh: