Butters AMT1800

[bigfellayork]

Thanks I’m on right track in my head then. On the rotary switch the connection nearest body is a single wire. As is the one at the bottom of the switch as you look in the pics. The rest running along the side are double wires into each terminal. Am I correct in thinking that the connections in pairs are the different tapping points on the coil and could you apply power at one of these pairs with switch out of the circuit, so I can check transformer alone. Thanks.

 

[bigfellayork]

Great thanks. Yes I’m aware of dangers related to the other taps while power applied.
The other pairs of taps will need to be kept apart in their pairs and not joined together but insulated off?
I should theoretically be able to measure each pair at rectifier side and note a voltage which then if I take a look at the switch should be able to work out if they are wired in correct location.
What is the role of the two singles that join at far left ( nearest the case ) and on underside as you view from pic. Thanks.
There are six power settings on the switch I’m assuming a 30amp jump on each setting based on min 30 amp max 180.

 

[bigfellayork]

 

[bigfellayork]

Far left shows a single copper wire. Then there is another single wire on underside hedden by the three sets of pairs in the pic. The brown insulated wire you can see at the top right of the switch at the back is the supply power.
Thanks again for your patience and time helping with this.
I’m going to use meter on continuity prior to applying any power to the wires to help me figure it out in my head.
Your diagram was exactly as I perceived.
Thanks again.

 

[bigfellayork]

On closer look at the pic you can see the second single wire just below the middle pair of wires.

 

[bigfellayork]

Yes they do all run to transformer. If power was applied to the single wires then that should theoretically give a max out put. But would each pair need to be bridged? Thanks.

 

[bigfellayork]

Got that. Thanks again.

 

[bigfellayork]

Update.
It appears to be the transformer.
Disconnecting from rotary switch and applying power to the two single wires tripped the mcb.
Testing with meter for continuity I took one pair at a time separated them and each one ran back to a single wire. ( one to one the other to the other single wire). This was fine for two of the pairs. The third pair showed each strand had continuity to both single strands not just one as the other two.
On the transformer top the layout shows the two single wires at opposite ends with the three pairs in between them.
The pair that appeared at fault were the first pair next to a single wire.
I then used one wire out of the next pair which ad continuity to the opposite end. Joined this and the other single wire to form a smaller transformer in effect. Turned on. No trip and the voltage was about 3v out.

 

[bigfellayork]

Not sure how much a transformer would be for this. Anyone any ideas on cost thanks.

 

[bigfellayork]

Point taken. Agree plenty of parts to upgrade another unit.
Plus side it was an interesting journey and thanks to your patience and knowledge we found the source of the problem.
Thanks again for all your input on this. A true gentleman.

 

[tinker jim]

Been watching this thread with interest enjoy the different aproachs taken to find/fix faults on transformer mig welders.
Have you considered taking the transformer apart and rewind it yourself always wanted to do this myself but as yet haven't had the need but think if it was needed I would have a go rather than scrapping straight off.

 

[tinker jim]

Yes I guess the wire is not going to be cheap if you use copper but would make for better duty cycle and I have seen the core cut with hacksaw carefully so as to be able to weld it back together after the repair but it' cost vs benefit.I must say I am surprised this set doesn't have a contactor could one not be added if components on circuit are caput.

 

[bigfellayork]

Well curiosity got the better of me with that deep seated feeling it might be fixable.
Un wound the outer primary cable. (That was fun). Deeper I dug the more apparent it all became.
This has been underwater for some time.
The corrosion on the pcb would go with that.
I’m prone to say it’s been about 6 inches deep in water.
The inner was actually still very damp and there was that smell of bog water as I cut into the insulation between the windings.
With that in mind I’m tempted to think the pcb will have crapped out as well.
Nothing ventured nothing gained.
The guts of another cheaper welder are going to get thrown in the case. The better wire feed and eurotorch will make it a half decent unit.
Thanks again for the effort on your part Pdg.

 

[bigfellayork]

Oh yes. By the time anything reaches my bins they are usually devoid of anything that could in anyway be recycled in the shed.
I’m staring at the removed winding now thinking of uses for it.

 

[tinker jim]

Least you know the reason for failure and in the process learning your way round a tranny mig is the wire copper or copper coloured aluminium.

 

[bigfellayork]

No it’s solid copper. It was a half decent tranny in its day.
It was very neatly wound and very well lacquered.
The water had penetrated through next too where the windings came out. Movement at assembly or just use had caused gaps for the water to penetrate through to the inner which is actually the primary not the secondary as I said earlier.
Jesus my head ain’t what it used to be.
It was the first time delving into a tranny welder and has been an interesting experience.
I do detest the throw away vulture we are in these days.
My shed is built from 18mm marine ply that was hoarding around some building works in a school. A few beers for the lads got that loaded on the back of my truck and it all kept nice and cosy with a stove made from an old gas bottle.
Long live the great British shed.

 

[tinker jim]

So unit was flood damaged and rather than dry it out properly they plugged it in and bang oh dear.I to detest the throw away society the world has become and a part of me would still want to rewind the transformer see what else needs repairing after but then I've never been any good at doing what i should do.silver lining could weight the copper in

 

[bigfellayork]

It was an old guy we gave him £50 for it. It was worth the punt. The young lad it is for already has a mig. Either Clarke or sealey I’m not sure. He has issues with the wire feed and wanted a eurotorch so idea originally was to get this and give it a look and if worth while then repair.
In this case I will pull his old mig apart and fabricoddle one decent welder from the two. So all is not lost.
Admittedly I would be possible to rewind the tranny and as far as the pcb goes its all through hole components so theoretically I could get every new component and swap out on the original board. The tranny certainly won’t be binned neither will the pcb and I may at some point give them a shot by rewinding the tranny and replacing the components on the pcb. I already have most of the resistors etc so there wouldn’t be a great deal to purchase.
The tranny would need new copper on both sides and looking at the thickness and length I pulled off that is definitely not cheap. I haven’t measured the length but I didn’t cut it deliberately so I could measure it if needed to buy new.
There are ways to calculate winding length and diameter but details for that tranny I cannot find so I don’t know what it’s out put on secondary at each point should be etc.
Ideally knowing it’s out put would help a great deal.
I live very close to Tecarc head office and the few times I’ve had to visit there the guys have always been very helpful.
Knowing how they work and the set up they have a wouldn’t give it a second thought buying either one of there own brand or the portamig or oxford ones both of which are all manufactured there. (They hold the rights to the portamig and oxford brand names).
They would more than likely have a tranny that would do or give advice or what spec it should be.
Not sure how bloody hard winding that copper on would be though. I had a good sweat going pulling it off.

 

[bigfellayork]

We have an induction hob cooker at home and it’s speed and ease of use is very impressive.
I may well use some of the copper to knock up a couple of induction toys. A nut heater would be nice. Does away with the blow torch on hard to shift nuts etc. I just like knocking stuff up to be honest. Made my own sheet folder and couple of other things.
I have my corner of old electrical items which get stripped when I get chance and all recycled into some project.
I’ve also got a strange fixation with these mini turbojet engines I keep seeing on YouTube. Fitted on carts or bicycles etc. If I can hide the project from the wife then maybe give one a go.

 

[bigfellayork]

Cheers that’s very good of you. On quick inspection nothing looked out of the ordinary. Just manufacturer obsolete.
Wiring diagrams would have been handy. In this case knowing the job in hand for each component would allow for possible changes to give better performance and reliability.
I tend to over engineer anything I have to build or repair.