Problem with uljanik-esab MIG welder

[chooowie]

Hy guys, I've got problem here & I need yours help. Everyone's invited to this riddle, especially YOU guys who are familiar with ESAB & hopefully ULJANIK units.
Thing is, couple of months ago, I was practically given almost unused MIG-MAG welder. It's 20 or so years old machine that has been bought brand new & it NEVER worked fine. Much as I heard about it, they tried to fix it, they called experts to service goddamn thing and it never worked as it should. Then, after maybe half of wire reel burned, they've put it in the corner and bought new welder that still works fine. This one that I've got, has practically never worked, it was parked in the corner of the garage & waited there for 20 years for someone to give him some attention.

When I brought it home, firstly I removed all side panels & cleaned everything with compressed air, I didn't want to plug it in the electricity and burn something inside. Everything inside looked perfectly new, without any signs of wearing or heating, unfortunately I don't have any pics of that, but I'll get some soon.

Welder is "uljanik LDA 400" rectifier with "esab a10 med30 synergic" wire feeder/ ctrl unit.

[/URL][/IMG]

[/URL][/IMG]

[/URL][/IMG]

[/URL][/IMG] In next few days I've bought bottle of CO2 30kg, new "messer" valve/regulator and new spool of 0,8 mm mild steel wire. It was time to try some welding and sh!+y machine just refused to give me any life signs. Seems that problem was in old esab standard joint where polycable enters wirefeed unit.

[/URL][/IMG] Trigger wire had bad contact with wirefeeder, when I've fixed that machine finally started to show some life in it.
Biggest problem now is that I can't get that fine flowing zzzzzzzzzz sounding transfer when trying to weld thin material, lets say 1 mm, if I turn power up I get burn through holes, but when I lover the power I get lot of dirt - spatter, high bead & ta-ta-ta machine gun like sound. Exit tips were clogging all the time. It felt like I don't have constant and stabile wire speed. First I've suspected that there's no enough pressure on wire feed rollers, but after few birdnests on rollers, I thought polycable was too long (4,5 meters) and it gives too much resistance to nice wire flow. I tried to press wire sideways in front of the exiting tip with 2 fingers and that was enough to stop the wire. Then I decided to shorten polycable in half to see if thet was the problem. Now I have 2 meters polycable and I cant stop the wire with my fingers but any welding is still impossible.


Guys please help, any advice is welcome and appreciated, I have no idea what to try next. I don't know what info you need to solve this problem, so you ask and I'll try to provide any info I can.


thanks a lot

 

[R Kraft]

Maybe check polarity.
Robert

 

[rtbcomp]

If it's been stood the chances are it will need a new torch liner, especially if you've fed rusty wire through it.

 

[chooowie]

2 r kraft- polarity is + on gun, - on ground
2 rtb- I've forgotten to say, liner was the first thing I've suspected & first to change, but it didn't help. When goddamn thing came brand new to the firm where I took it, it only welded about 1 and half of 15 kg reel, nothing more. When I bought it, I've also bought new wire. This machine has never seen dirty wire. That's why I decided to shorten polycable. Now it's mission impossible to stop the wire, but still welds like sh!+.

 

[Glyn]

That's a monster of a welder for home use, isn't it? Are you sure your using the correct imput voltage?

 

[chooowie]

Well, it is true monster, industrial heavy duty machine, it was built in corporation whose main occupation is shipyard, one part of that corporation is specialized for building welding machines. Not that I need something like that at home for my hobby, but it was practicaly free. If I had to buy welder on the regular price, I wouldn't go over 200 amps. It's 3 phase welder, running on 380V, I didn't measure voltage at the socket, I don't think that might be problem, becouse there was same problem even when it was working in the industrial zone, on their electric net. What is bothering me is what does that mean 3 phase?? what is 3 phase electricity in it's nature?? Does that mean there is 3 different levels of el. potential or 3 phase stands for something else.


I mean, what if I've connected wires wrong way, phase wires of course not the earth wire. I would gladly call expert to take a look at it, but I wanna use this opportunity to learn something first, besides, when U have no clue about the problem, who ever solves the problem, can easily say : I had to change everything!!! That can make ignorance very expensive.

 

[shenion]

It does show 3-phase on the spec plate.

There should be 3 power lines and a ground (possibly a neutral also, but that is rarely used.)

If you just connected two phases, the voltage will be low and the power to the wire feeder might also be low. A picture of the connection terminals might help.

I have run 3-phase units on single phase. Takes a bit of doing and some will never work right without major changes internally.

There also looks to be 3 + outputs: A, B and C, probably different inductor taps. Try it on C and you will probably find a smoother output. The + output does go to the wire feeder?

 

[chooowie]

I'll take some detailed pics of internals, I think I saw that those ABC+ outputs are all on same lead inside, if so, what would be the point of having 3 of them, maybe power source for additional wire feeder??
Big question for those familiar with esab units : what SYNERGIC stands for, what that means? Could it be some sort of self adjusting gremlin inside who takes care about voltage/amperage characteristics?
Q for electricians: how voltage & amperage depend on each other?

 

[chooowie]

For Specialist and others from this part of Europe: could someone please help me about getting some kind of user manual, or any kind of book about ULJANIK LDA400? I tried calling and mailing to ULJANIK SZZ (szz stands for Strojevi Za Zavarivanje - welding machines) guy promised me to try finding something in their archive but even after few calls he never responded to me.
Then I tried contacting ESAB, they have sent me few pages about their wire feeder but nothing that would be useful to me.
If anyone can provide me some info about those machines, I would very much appreciate it.

 

[Specialist]

I have some experience with this machine, since we have a few in active use. And we never had one go bad or perform poor really, but going on that symptoms your machine has, I would venture to say that you probably have a diode problem within the rectifier bridge. It is consistent with your problem; a partly faulty rectifier bridge causes insufficient and sporadic arc at low settings, and burn trough at higher settings (since this machine can give out large amperage, it can work somewhat even with a few diodes out, but it cant work properly).

In effect, if that really is your problem, you can check it by taking the machine apart, disconnecting the diodes and measuring theirs resistance in both ways. Off course, disconnect it from the mains plug beforehand and short out output leads (while machine is off and disconnected) as to discharge any potential charge left in it. Diodes should be measured in both ways, and resistance to current in one direction should be much less then the other, and all of the diode's low and high readings should be close. For example, if D1 reads 500 Ohm, D2 490 Ohm, D3 503 Ohm, and D4 reads 800 Ohm, D4 is defective. The same holds true for low range of resistance. Also a diode is defective if it has either infinite or zero resistance in both ways.

It would be useful to see pictures of the inside of the unit, from a few angles, so that maybe I can spot an obviously defective component or wrong connection, a long shot but maybe...

It might be as simple as a bad contact tip, poor connection, or not adjusted correctly?

On ESAB feeders, synergic stands for pre-programmed so called synergic lines (that are in fact corresponding programs for selected profiles for welding mild steel, stainless, or alu). So for example, if you put it in synergic mode and select wire diameter, shielding gas, and voltage - then wire feed speed will be automatically corrected to correspond with the best synergic line for selected metal, and those lines are factory pre-programmed in the feed unit. Also, MED 30 synergic comes with spot and interval welding modes thrown in.

For your use, it's best to fine tune it manually, bypassing the synergic lines. From your picture I see that top most switch is in continuos bead position, that is ok, middle one is on manual, that is also ok, but lower switch is put on cored wires. Left is cored wire, right is solid wire. If you are using solid wire, it should be put to the right.

How voltage and amperage depend on each other? I cant go into details right now, but, for all fits and purposes, wire speed is the single most important control on any MIG/MAG machine. Since voltage is effectively stable (within the voltage setting that is chosen), we can say that amperage is controlled by means of wire speed. And that means - more wire speed, more amperage. That goes up to a point, then we need to select next voltage step up, and then again tune it finer with wire speed.

I recall that a,b and c outputs are mentioned somewhere in the original documentation as "soft", "medium" and "hard" outputs as referred to the arc characteristics. I might be mistaken on this, I have to check.

I would suggest that you try the following: first check the contact tip, replace if necessary, tighten up properly all connections, then flip that switch on the right for solid wire selection, and try to pull a nice bead on say 3 to 5 mm steel. Set wire diameter (or voltage really, as thats it) at 0,8 to 1,0 and start with wire speed at about 4 and work your way up from there until you get a nice steady burn and proper penetration. Then if machine works proper here, you can try to lower wire diameter slightly (by 0,1 to 0,2), back off wire speed and try thinner material, should work ok. Also, keep gas flow at least around 10l, maybe up to 14l.

If this doesn't work, then you can try to diagnose the diodes if you know how and have experience, otherwise seek help from a professional electrician. Last thing you want to is to dabble around the current source without firm knowledge of what your doing, as it can be very dangerous, always deal with it with extreme caution.

And at last, I would not mind a bit if someone gave me something like that, as a pro welder is lets say, quite rare to come by If you want to get rid of it, send me a pm hehe

 

[chooowie]

Wow, now that's a hell of an answer. I have to admit I didn't expect such detailed explanation, this is surely pleasant surprise. I'll get some pics of internals as soon as I manage to take welder out of my garage and disassemble it. Right now i have barricades inside, a friends car actually, so I cant move welder anywhere. About the price of the machine, I wrote earlier that it's been given to me. Actually, I work in one big firm as a mechanic/ machinist, last year I've repeared something that nobody expected that could be done and saved some substantial money to the firm. When I showed interest for that welder, I think that was reward for that yob from earlier. & I don't wanna get rid of it, I wanna sleep with it, hehe. Thanks for such a detailed answer.

 

[chooowie]

Some fresh pics of internals here http://rapidshare.com/files/210496558/uljanik-esab.rar.html too many of them and to big to upload them here, almost 100MB.
Specialist, you were right about ABC + exits, I thought they are all connected on same lead, but they are only attached to same carrier on the chassis, but every one has it's own lead from another coil.
Question about rectifying bridge diodes: I've seen earlier rectifier diodes on radios and such things that run on 220 V, and there is 4 of them. One guy who knows little bit about those things, sort of explained to me how those diodes work. But what happens when we talk about 3 phase electricity?? Would there still be 4 diodes or 6 of them??? I'm asking becouse I didn't find anything that I expected diodes in welder would look like, but I've seen 6 peaces of something in line between coils and ABC + exits, I don't know what would that be but it's got huuuuuuge aluminum coolers on it. I tried to get some god and clear pics from different angles, I hope this would bring some light to the problem. If someone can choose some better pics from link above and transfer them in to this topic, that would be great.

 

[Jake SS]

The diodes are at the bottom bolted to the alluminium busbar with the white insulation on the tails, undo the diodes at the busbar and check each one individually with meter set to diode test and measure each one with probes touching one end to the tail andthe other probe to where it is bolted to heat sink, you should get a voltage drop eg 1.7 volts one way and open circuit when changing polarity of meter probes.

Have you checked the fuses? the 3 large white things at the back on one side, they should screw out from memory.

Check contactor for continuity when it is pushed in. If you feel confident you can check for voltage drops when contactor is activated. Between phases on the output side T1 to T2, T1 to T3, T2 to T3 and from L1 to T1, L2 to T2, and L3 to T3

Try this first

I am assuming that you have checked everything else that other posters have suggested

Cheers

 

[chooowie]

I've checked fuses first, when I brought it home, after cleaning everything with compressed air, before plugging it to the electricity. I shell try diodes next, maybe tonight if I catch some time. If diodes are OK, then search goes on to the contactor and those phases. Thanks a lot guys for all yours input.