Eland mig 130 with issues

[GraemeVW]

I thing the splashyness as it's been called, I would call stuttering.
Cleaning the feed roller helped, as did tweaking the spool drag more. I guess it also could be the wire sticking in the tip but it doesnt quite feel like that.
For now, it has gone away, but as I think I've mentioned I'm not yet sure it's permanently gone away.
I did try to weld through it a couple of times, it seemed to stutter, go back to welding nice for another inch, then stutter again bit worse. It does give the impression of something getting hot, or increasing in resistance.

 

[GraemeVW]

I think a111r is referring to the main, 4-stud-diode rectifier ( not the small one on the PCB ).

Hmmm, trying to remember what it looks like inside, not quite sure unknown which one were talking about then.

 

[GraemeVW]

I think a111r is referring to the main, 4-stud-diode rectifier ( not the small one on the PCB ).

This?

I've not even looked at the back end of the welder yet, apart from blowing the dust off. I'd sort of wondered what that was.

That's not my welder btw, but pretty much the same inside.

 

[GraemeVW]

I assumed he ment this one

 

[a111r]

^^ That looks like a large ceramic resistor.

Yes, sorry, I was talking of the main rectifier. That is a nice old one above. Stud mounted diodes into proper heat sinks.
My simplistic thinking is that MIG PCBs are doing a couple or three things related to switching and motor speed.
Maybe 99% of the time they either work or don't, but rarely (if at all) will the PCB's components affect the actual welding voltage / arc quality.

Your previous thoughts were spot on in thinking that it's still got a problem. Nicer pro kit like this shouldn't be so fussy.
"It is welding ok again now but is a little fussy about set up. It seems to have a wide window of settings that will weld stuff but a narrow margins where everything has to be right before it will weld nicely. My old Clarke would just blow holes, or not penetrate, and when you got it between those, that's where you welded. No real ability to finely adjust".

 

[GraemeVW]

Yes, sorry, I was talking of the main rectifier.
My simplistic thinking is that MIG PCBs are doing a couple or three things, that 99% of the time they either work or don't, but rarely if at all will the PCB components affect the actual welding voltage / arc quality.

Your previous thoughts were spot on in thinking that it's still got a problem. Nicer pro kit like this shouldn't be so fussy.
"It is welding ok again now but is a little fussy about set up. It seems to have a wide window of settings that will weld stuff but a narrow margins where everything has to be right before it will weld nicely. My old Clarke would just blow holes, or not penetrate, and when you got it between those, that's where you welded. No real ability to finely adjust".

So the big bank of 4 things (diodes i guess then) by the fan is the main rectifier.
I've not been anywhere near that yet apart from to check the connections aren't loose.

The other thing, as I mentioned somewhere, that makes me think there is still an issue is the previous owner said it worked fine, then got hot, and started playing up.
After doing the pcb work it still had the fault. I seem to have worked round the fault by optimizing the wire feed, but that isn't what caused the original owners issue so there must be something else and I've just managed to find a sweet spot where it is sort of ok.

I think I'll strip it, clean everything, see if I can check the caps in any way and test the big diodes.

I'm going to assume, if they are dodgy, things might get a bit more expensive!

 

[GraemeVW]

I know it's only 130amp, but it also seems reasonably happy welding 1.2mm ish plate with any setting I give it, which also seems a little odd. It won't penetrate properly if set super low and will blow holes if I'm not fast enough on max, but it's not as deffinate as id sort of expected.

Voltages tip to earth were 17-28 iirc, or something like that.

 

[a111r]

Yes a clean up will be worthwhile, checking for bad joints, such as this work return lead's dinse plug:

 

[GraemeVW]

The second circled thing on the pcb isn't a ceramic resistor. At first I'd assumed it was a cap, but it's a bridge rectifier. Only realised that this morning. Alot of diodes on that board.

That earth connector looks horrid!

Just had a quick look to see what the main diodes are. Skn 100/02.
Quick search tells me I'm not getting replacements. Also seems this type of diode are expensive, but looks like modern equivalents may be available and alot cheaper.
I don't really understand them though. I'll have to try and work out what the important values are and see if I can find something else that will do the job, and aren't £50 each!

That's if they turn out to have issues. They may well be fine.

It's the same for the caps, £50 a piece if I want something that is pretty much a direct replacement.
I'm sure I could find something that will work cheaper though.

Just means I can't go replacing parts just in case without finding out for sure if they are broken or not.
Also means I'll need to find out for sure what it needs, if anything, before I replace any of it or I could easily be in a situation where I've spent loads, need to spend loads more, and could have just bought a brand new machine!

So, if anyone knows of an affordable equivalent to skn100/02, or a cheap source for bolt in 10000u 63v caps, let me know!

 

[GraemeVW]

Skn 100/02 seem to be, anode to pin, 100amp, 200v.
Seems I can probably get ones with higher voltage limits, higher current limits, or both. Not sure about mounting sizes yet.
Still looks to be £100 to replace all 4, which is guess I'd have to if not replacing exact like for like.

Hopefully they are ok!

 

[octo0072000]

daft question try using 0.8 wire see if it makes a difference

 

[GraemeVW]

daft question try using 0.8 wire see if it makes a difference

I probably will eventually. This welder has always been run on 0.6, and 0.6 is my happy place, so I just followed suit.
Only got 0.8 on hobby reels at the moment though that this won't take untill I make an adapter.

Even if it works better on 0.8 though, I would still rather use 0.6.
I know alot of folk don't like it but I do.

When my friend has finished his current reel (he is building a train, so using alot of wire!) I was going to wind my 0.8 onto it so I can try it on this.

 

[a111r]

Those old stud diodes are probably more reliable than the modern press fitted type.
Anyway, test them cold and hot, as suggested.
Would be nice to keep them original but otherwise, cheaper alternative rectifiers could be fitted.

The smoothing capacitors could be tested and re-formed.
If duff, they can just be left in, the machine will still work nearly the same.

 

[GraemeVW]

Those old stud diodes are probably more reliable than the modern press fitted type.
Anyway, test them cold and hot, as suggested.
Would be nice to keep them original but otherwise, cheaper alternative rectifiers could be fitted.

The smoothing capacitors could be tested and re-formed.
If duff, they can just be left in, the machine will still work nearly the same.

Seems 100/02 aren't made any more, but 100/04, 08, 12 etc are and they seem to all be m12 a d the higher ratings won't matter.
Not cheap, but shop around and I may be able to replace them for £60.
No idea what other option I'd have.

I'll have to read up on the caps to see if I could test them at home. I've no idea how yet, but I do have an oscilloscope. Maybe I could use that in some way. Maybe build them into a circuit and test. I don't know, I assume the internet may throw up some options.
It's just a bank of caps though. I could probably sort out some kind of replacement. At least they are low voltage. Big capacitance high voltage caps can get expensive! I found that out building amplifiers.

I have to bear in mind how much money it's worth throwing at this though.
I am happy to put in whatever it takes in effort, but don't want to end up spending £250 fixing it.

I'll pull it apart tomorrow afternoon and see what I can find out, then no doubt ask some more questions.

I'm teetering on the edge of my knowledge with this.
Still, I've got this far!


Edit
Quick search shows me the reforming process should be straight forward and that itself will tell me if they have come good or if they are dead.
I'll practice on some old caps before these ones though.

 

[hermetic]

I think I would be happy with the welder as is now, try an overlap weld on two bits of 1.0mm sheet or similar, and make sure they are clean and bright. When I swapped from .6 to .8 the first difference was in the shop, it was cheaper! Don't know if this is still the case, but it did stop a lot of the burn through. You do have to experiment a lot with wire feed as the simpler single phase wire feeders are sometimes not brilliantly stable. As I said before, I am using an ancient Maxarc mig 200 transformer machine with a variable transformer rheostat type speed control which gives very fine adjustment, and the feed motor is a real peice of engineering perfection. and I am welding 1 + 1mm with no blow through, and the welder will go lower! It is much smoother than the single phase clarke 175 I used to use. Get into a project with it and see how it performs!
Good luck
Phil

 

[GraemeVW]

I think I would be happy with the welder as is now, try an overlap weld on two bits of 1.0mm sheet or similar, and make sure they are clean and bright. When I swapped from .6 to .8 the first difference was in the shop, it was cheaper! Don't know if this is still the case, but it did stop a lot of the burn through. You do have to experiment a lot with wire feed as the simpler single phase wire feeders are sometimes not brilliantly stable. As I said before, I am using an ancient Maxarc mig 200 transformer machine with a variable transformer rheostat type speed control which gives very fine adjustment, and the feed motor is a real peice of engineering perfection. and I am welding 1 + 1mm with no blow through, and the welder will go lower! It is much smoother than the single phase clarke 175 I used to use. Get into a project with it and see how it performs!
Good luck
Phil

As this is right now I can easily weld 1mm to 1mm, butt or overlap, with no blowthrough.

Edit to say, yes, try a project with it, see what it does, is a good plan.
I'll pull it apart, check the caps and all the connections, clean it properly, then just use it.

 

[GraemeVW]

Good progress there.
I have had a similar 'step change' type fault like this ("welds lovely for 1" then goes splashy")

The cause was rectifier diode partial failure. The voltages can test to spec. fine, like yours did.
The diodes too, on the 9 volts from the DV meter's diode test function.
In operation, not so. Try heating the diodes with a hot air gun and then test them?

Just tried this.
Not sure exactly what the diode setting on my MM is telling me, but I disconnected all the diodes and they test fine. I warmed them with a hot air gun on high for maybe 30 seconds, right up close, and you can watch whatever the MM is ready slowly reduce in value. Let them cool and it goes back up.
Don't know what would happen if you got them too hot to touch, not sure how far to go before I'm basically destruction testing them.

But, I'd say they are ok.

I might run the welder for a while and see how hot they get and test them again.

I'll still pull It apart, and probably try reforming the caps just in case, but I'm glad the diodes seem good.

 

[a111r]

The thermal cut outs on the rectifiers and transformers are often rated at around 100C, so I'm not sure about that performance?
I did the same a you when I suspect two partly dead diodes (quick blast with a heat gun) and the changing values I think confirmed it:

Vintage Migmate ... reunited!

Going to be poking about this old machine which I sold 6 years ago. Didn't realised then that it was of superior build quality.

www.mig-welding.co.uk

I had a suitable rectifier in stock so used that as a replacement.

Post #1, "He thinks it got hot. Now it welds fine for an inch then plays up. He assumes it's a pcb issue".
If you're welding thin / car stuff, then it may not get hot and so perform fine...

 

[GraemeVW]

The thermal cut outs on the rectifiers and transformers are often rated at around 100C, so I'm not sure about that performance?
I did the same a you when I suspect two partly dead diodes (quick blast with a heat gun) and the changing values I think confirmed it.

Post #1, "He thinks it got hot. Now it welds fine for an inch then plays up. He assumes it's a pcb issue".
If you're welding thin / car stuff, then it may not get hot and so perform fine...

I can test them further, just wasn't sure what to expect.

So I can get the diodes to 100c without killing them? At that point what will happen?
I assume falling values are to be expected, but at a certain rate and maybe not below a certain figure?

I am just not sure exactly what to look for in the test.

Am in looking to see when the thermal cut out happens?
I have a temp probe too, I can get very thorough with it, if I know what I'm looking for.

 

[a111r]

Yes easily 100C, but for how long, I don't know.
Semi-conductors can take the heat past soldering temp (above 240-ish C ?) and the spec. sheets do give a temp. limit.
(I'm not an expert here...)

If the forward voltage drops 'a fair bit' with heating up, maybe that's enough to expect the welding voltage will potentially suffer decreases, to the point where the wire just glows red?
Anyway, I'd strip it down, clean and check first.