Eland mig 130 with issues

[GraemeVW]

@a111r
It doesn't go that far!
It just stuttered.
So the multimeter is giving a forward voltage reading?
Open in one direction and .435 in the other.
When heated with a heat gun I think they went down to about .270 before I stopped.
I don't know how far then would go though, or how hot I was getting them.
The fact they are on pretty big heat sinks suggests they can take some warming!

Do those numbers spell trouble? Would you have expected the readings to not change at all, or hardly change?

I don't really have a frame of reference for what to look for. They all did the same thing though, which suggests they have all failed in the same way, or they have all degraded the same amount, or they are all still fine.

I found the data sheet for the skn 100 series, but I don't understand a word of it!

 

[GraemeVW]

I have them out and on the bench. Whole welder is now apart. So I can test further if you think there is more to find out.

 

[GraemeVW]

Internet tells me the forward voltage will drop with every degree. Hard to find specific info, and I'm.sure all diodes are different, but it seems maybe the amount they are dropping and how much I heated them may not be that far off normal.

I'd me more concerned if they were all acting differently, or if they dropped rapidly, or even went open circuit when hot etc.

 

[GraemeVW]

I figured it may work better if I cleaned the front plate.

 

[GraemeVW]

Sent an e.mail to the manufacturer, never know, they may be able to give me some deffinate test parameters. If they are faulty I guess I'd have to use 100/04 diodes. They seem to be the same but with a higher voltage limit.

Edit, skn 100/08 are 2/3rds cheaper!

 

[a111r]

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.

I missed this post yesterday.
So that is sounding like bad joint somewhere, creating high resistance, if the 6 voltage settings aren't making much difference!

On 1.2 mm steel, you'd normally be using either voltage setting 1 or 2.
Voltages 3 to 6 would easily blow through, unless you had the wire speed (amps) set unrealistically low.

 

[GraemeVW]

I missed this post yesterday.
So that is sounding like bad joint somewhere, creating high resistance, if the 6 voltage settings aren't making much difference!

On 1.2 mm steel, you'd normally be using either voltage setting 1 or 2.
Voltages 3 to 6 would easily blow through, unless you had the wire speed (amps) set unrealistically low.

I have it set on 4 at the moment, wire speed probably about 8, but the wire speed trimmers have been adjusted before so I don't read much into the wire speed settings just yet.
At that setting the bead is penetrating 1-1.2mm (ive not measured it) consistently, it only blows holes if I stop.
I suspect at the moment the lowest wire feed might not be slow enough but I figured there is no point setting the high and low speed trim post untill I know the power is right. I can then make sure wire feed feels appropriate.
Unless I can find out what speed the wire feed max and minimum should be and set the trimmers that way.

A bad joint creating resistance would make sense I guess, maybe the initial burst of current gets through fine then resistance build, making it splutter.

As I say, it's apart now. I will clean and test everything as it goes back together and make sure everything is tight with good contacts.
A couple of connections weren't as tight as I'd have done them up, but weren't loose. No connections looked bad, but you can't always tell.

At voltages 1 or 2 I can't seem to get it to weld very nicely on this plate, feels like I can't get the wire speed down enough, which could also mean power is low. Tip voltages tested ok, but that doesn't mean it's passing enough amps.

The 6 settings do make a deffinate difference, just feels like over a narrower range than I expected and not necessarily over a range that works well with the wire feed range.

I suspect a good clean up and sort out will help.

I've no idea if the previous owner fiddled with anything to see if he could fix it when it started playing up. I suspect he did, but not much.
Both The high speed and low speed trimmers were on the stops.

 

[GraemeVW]

I took this whole thing apart and cleaned everything! Looks loads better in here now.

I checked the caps the best I could, resistance checked, then put some voltage in them. They all took the voltage instantly and held it. Only put 12v in them though.

I retested the diodes, I'm still 80-90% sure they are fine.

I took the contactor apart and the main contacts were horrid, so cleaned those up and put it all back together.

I'm as sure as I can be that everything is spot on.

Plugged in, turned on, fuse didn't blow, it didn't set on fire.
Run through the controls, everything works. Must have put it back together right.

I'll put the wire back in after a cuppa and see how it welds.

The wire feed sounds better though. Not sure why or how. Must have been the contactor contacts.
Before when you pulled the trigger it seemed to almost start fast then instantly drop a little speed. Doesn't do that any more.

I'll find some clean offcuts and try a weld. If its not embarrassing, I'll post pics.