Mother of holly crap, the bastard is just not giving up!!

[Behemot]

Look at this crap from Einhell ISG 1000/1 welder!!

[tom66]

Re: Mother of holly crap, the bastard is just not giving up!!

Looks like it could have vented due to overvoltage and managed to survive the event, amazingly.

[Behemot]

Re: Mother of holly crap, the bastard is just not giving up!!

Something on the secondary is shorted, either one of the fat TO-263 rectifiers (C16T20F) or the IB74 BKH transil (?). Primary seems fine, no shorts anywhere.

The question is if the cap blew because of overload or it blew before and because of voltage and current spikes on secondary the rectifiers blew than.

[ben7]

Re: Mother of holly crap, the bastard is just not giving up!!

WOOOOOOOOW!

That sucker was blown HARD!

Could have been one of the diodes that shorted, putting AC through the capacitor, that would certainly make it vent like that.

[Kiriakos GR]

Re: Mother of holly crap, the bastard is just not giving up!!

Do not search for logical answers in a poorly designed circuitry with out a damn fuse.

[Behemot]

Re: Mother of holly crap, the bastard is just not giving up!!

It has fuse, even though on neutral (?!) instead of phase. But the primary seems OK, no rectifier or transistor blown there.

Problem is with secondary. I found this invertor was not really wery well rated by ppl. It is rated for 80 A, but being able to work only 15 % of time at 80 A output. No wonder, if you multiply 16 A (superfasts rating) by 5 (their number) you get 80 A but we all know it's not really how it works with diodes. Also the cooling system is weird, the diodes are soldered on PCB and the PCB itself is screwed to cooler. So the heat has to go through the PCB material first which is not really a good conductor!

If I will even succeed in contacting the owner (I got this thing here for so long I don't even remember whose it is ), I'll recommend him replacing the rectifiers with 30A schottkies from STMicro, they should have like 15 W less burned power and provide that 80 A for some reasonable time.

[tom66]

Re: Mother of holly crap, the bastard is just not giving up!!

This is very common with poorly designed inverters
http://ludens.cl/Electron/chinverter/chinverter.html

I call any watts figure on an inverter that poorly made "marketing watts".

[momaka]

Re: Mother of holly crap, the bastard is just not giving up!!

I call any watts figure on an inverter that poorly made "marketing watts".

Ratings like that have a proper name - ILS (If Lightning Strikes)

[Behemot]

Re: Mother of holly crap, the bastard is just not giving up!!

Seems the heat transfer is not that bad - I was hardly able to desolder the transil, which was bad, using 60W pen (the high-power one, no micro-crap) and 125W trnasformer pistol. Will have to resolder the output joint which I tore out, probably using hot air and two pens (60+80 watt)s because it is insane.

Any idea what the transil is?

[japlytic]

Re: Mother of holly crap, the bastard is just not giving up!!

Could it be caused by excessive ripple over time?
I know the capacitors in welders can be worked quite hard (frequent high charge/discharge rate).

[Behemot]

Re: Mother of holly crap, the bastard is just not giving up!!

Seems plausible. May it be 74 volts? This thing makes quite a low voltage (it is also known for being difficult to light arc with), around 40 volts so something like 75 votls transil may be just the right one.

[Behemot]

Re: Mother of holly crap, the bastard is just not giving up!!

I needed to heat that thing on a like 2000 watt cooker first to be able to do any soldering there. Was not able to heat it properly even using 80W soldering pen and I_don't_know_what_wattage soldering iron for gutters simultaneously. The latter gave up in the process…

Will now try to solder it together and see if it fires up. However, I don't have big caps enough, closes I have is Crapxon 420 uF/450 V and than only 390uF Rubycons…can only maybe squeeze a 100uF/400V KXG in parallel in there, somewhere…

[Behemot]

Re: Mother of holly crap, the bastard is just not giving up!!

It shorted immediatelly again going into protection mode, I am not wasting time with this thing any longer.