Inverter Welder Strangeness

[Crystaleyes]

Re: Inverter Welder Strangeness

being dc it should weld stainless steel

Apparently so. In the user manual, it lists 2.5mm as the correct SS electrode.

It also has an optional TIG capability

[petehall347]

Re: Inverter Welder Strangeness

being dc it should weld stainless steel

[Crystaleyes]

Re: Inverter Welder Strangeness

Thanks for all the comments, and yes, lessons have been learnt and invaluable experience gained.


Just a final word regarding this welder as I've never used one of these new-fangled contraptions before, and that is that this welder is a beast!

Not sure if it's just because I've never welded using DC, however this welder is way more powerful than I had imagined. It's easy to see why they are so popular.

Light, therefore portable, and capable of welding metals to an impressive thickness for its size.

That said, having worked my way through it's circuitry, it is also clear that in the future there will be a steady supply of inverter welders needing repair.

[petehall347]

Re: Inverter Welder Strangeness

i did wonder about that solder joint but dismissed it as i thought it had been sorted along the way

[CapLeaker]

Re: Inverter Welder Strangeness

All true.

Perhaps the most valuable lesson here has been not to rely 100% on a pcb being good just because it recently came from the factory, and was essentially 'as new'.
After the initial pwm section repair, I had been going in circles and getting lost lookng for bad components, when the problem was hidden under the varnish on the actual board.

I suppose that considering I took two months off in the middle, and probably another month waiting for parts, then it's not soooo bad, but I need to speed up if I ever want to work as a repair tech.

Once again, big thanks for the input, as well as yours and everyones patience.

No problem. Just remember the snapping noise and I told you to investigate where it comes from. Always fix what you know isn't right or looks off, before you go down different rat holes. It's always good to take a breather and go back to the basics. Look at my plasma cutter repair or a few other complicated devices that I did… it all took some time, but it got fixed at the end. Sometimes you got to trust yourself a bit better. You'll get there… maybe not fast, but in time you will. You get faster as you gain experience. More experience, more $$$.

[sam_sam_sam]

Re: Inverter Welder Strangeness

You have to gain experience and what you when through is how gain the experience

[Crystaleyes]

Re: Inverter Welder Strangeness

All true.

Perhaps the most valuable lesson here has been not to rely 100% on a pcb being good just because it recently came from the factory, and was essentially 'as new'.
After the initial pwm section repair, I had been going in circles and getting lost lookng for bad components, when the problem was hidden under the varnish on the actual board.

I suppose that considering I took two months off in the middle, and probably another month waiting for parts, then it's not soooo bad, but I need to speed up if I ever want to work as a repair tech.

Once again, big thanks for the input, as well as yours and everyones patience.

[CapLeaker]

Re: Inverter Welder Strangeness

I said in the beginning, that sometimes you have to take a break and look at this later again. Congratulations to finally fix this thing and now you have learned quite a few lessons. Given it did take quite some time, but you gained quite a bit of knowledge and got as a result a cheap working welder!

[sam_sam_sam]

Re: Inverter Welder Strangeness

Yes very well done

[petehall347]

Re: Inverter Welder Strangeness

well done

[Crystaleyes]

Re: Inverter Welder Strangeness

OMFG!

It Lives!

It's alive, I tell you!!!

Fuck yeah!

So, after four months, I think it is safe to say that the problem was poor connections between the mains input and at least one of the 2200uF caps.

Remember that this welder was bought (broken) in order to learn how these inverters work (at least more or less) and that mission has well and truly been achieved.
Just returned from the garage, where the welder laid super clean welds for the first time since I bought it.

Ok.. It took a carbonised pcb to finally reveal that the problem was hidden under the green varnish, but these are all invaluable lessons.
Performing resistance tests today from each point of the mains input/rectification section, revealed that two of the traces had breaks in them, even though before the burnout they had 'appeared' (to the eye) fine.

Invaluable lessons in my electronic repair journey...

I wanna thank all who have given their time in this thread, but especially CapLeaker, as he dissuaded me from scrapping the welder when I was itching to do just that!

Posting the pics of the pcb repair, for posterity...


... Or was the problem solved because I changed the red (stop) on/off switch, for a green (go) one?

[Crystaleyes]

Re: Inverter Welder Strangeness

add a fuse if your mains plug hasn't already got one
also check the caps aren't shorted

Gonan do that

[petehall347]

Re: Inverter Welder Strangeness

add a fuse if your mains plug hasn't already got one
also check the caps aren't shorted

[Crystaleyes]

Re: Inverter Welder Strangeness

You could use stranded, just make sure to soak it all the way with solder. But I prefer solid core.

This was actually why I thought of desoldering wick. I have some already soldered all the way along...


This trace only goes from the mains switch wire to both the 2200UF caps, so it shouldn't be such a problem (he says...)

[CapLeaker]

Re: Inverter Welder Strangeness

You could use stranded, just make sure to soak it all the way with solder. But I prefer solid core.

[Crystaleyes]

Re: Inverter Welder Strangeness

The AC mains wires to the pcb are 4mm stranded, so I was thinking of that, or perhaps even desoldering wick, mainly for ease of use, but are you suggesting to use two or three solid core wires instead?

I have 2.5mm solid core here for sure. I suppose 3 of these would be more than enough.

[CapLeaker]

Re: Inverter Welder Strangeness

Make a few runs using solid core.

[Crystaleyes]

Re: Inverter Welder Strangeness

The black carbon is conductive and gets worse if high humidity is in the game. You have to get all that black stuff removed using a rotary tool or cut it out and fix the hole and the trace. It's a wide trace, so it needs to support a lot of current.

I've cleared out all the carbon, which left a fair hole, so that has been filled with resin and is now setting. I'm not gonna attempt to repair the traces, but rather use flex wires to bridge the points of contact.

I'll be back tomorrow when it is all dry and fixed.

[CapLeaker]

Re: Inverter Welder Strangeness

The black carbon is conductive and gets worse if high humidity is in the game. You have to get all that black stuff removed using a rotary tool or cut it out and fix the hole and the trace. It’s a wide trace, so it needs to support a lot of current.

[Crystaleyes]

Re: Inverter Welder Strangeness

I had been seriously thinking that the fault was due to a weak link somewhere. I'd been checking all the removable connections through the mains switch and also from the board to the welding cables outputs.

Before I went to the garage today, I ran the welder for a good 15 minutes or so, taking readings and the pwm section through the IGBT's appeared to be on the button.
There was a stable 46KHz frequency with a 50% duty cycle, and without any load the machine appeared fine.

Anyway, now gonna clean it all up and have another good look, coz at the moment the burnt trace is still sparking and glowing when the machine is running, even though there is no longer any clear electrical connection.
How this welder stills turns on when one of the two AC mains inputs has a severed trace is gonna be interesting to see.

The solder station is on.

I'll be back...