Good day all,

 

I've had a really crappy day so far.

I went to buy some steel to make a security gate (instructions from SWAMBO). While inside someone broke into my Toyota Hilux and tried to steal it, broke the ignition, but thankfully I have an immobiliser.

R1500 later, (call out to remove ignition and steering lock, then replace ignition) I'm back at the steel place to load my steel, get back home and start my project.

Then one welding lead breaks clear off right inside the handle, no biggy, I get that fixed and continue to weld.

15 minutes later BOOM, the welder blows and also trips the mains.

I open up the inverter and find this.

Any suggestions, SWAMBO wants to know when I'm going to finish the gate 

Can't remember where the favourite spares shop are still in that area. Else Communica would most likely have

Do you think its just this component though, what would have caused it?

13 hours ago, Antony said:

Do you think its just this component though, what would have caused it?

That looks like the "source" pin of the FET, so it likely just blew from working too hard. The main current switched by the thing is on the source to drain (middle and right) pins. Gate is usually on the left, drain in the middle and source on the right when holding the component up facing you with the legs down. But consult the data sheet if in doubt.

You can take it out of the circuit and measure the resistance from gate to drain and source. FETs have a large resistance (or a small capacitance if you will) between gate and the rest. If that isn't shorted, you should be fine.

Overall, if the gate is important enough, I'd get a cheap oil-bath welder or even a smaller inverter welder to finish the job, and then just sell it on afterwards on gumtree... or fix the blown one and sell that on. Sometimes time is more important... as you probably discovered :-)

Edit: Better yet, get a cheapie on gumtree to tide you over. Lots of welding machines for sale over there usually, sometimes even the odd mig welder too.

Edited October 20, 20186 yr by plonkster

Come to think of it, this also tripped the power. It might have been shoot-through, which means the other FET might be a little worse for wear too. Replace them both.

3 minutes ago, plonkster said:

That looks like the "source" pin of the FET, so it likely just blew from working too hard. The main current switched by the thing is on the source to drain (middle and right) pins. Gate is usually on the left, drain in the middle and source on the right when holding the component up facing you with the legs down. But consult the data sheet if in doubt.

You can take it out of the circuit and measure the resistance from gate to drain and source. FETs have a large resistance (or a small capacitance if you will) between gate and the rest. If that isn't shorted, you should be fine.

Overall, if the gate is important enough, I'd get a cheap oil-bath welder or even a smaller inverter welder to finish the job, and then just sell it on afterwards on gumtree... or fix the blown one and sell that on. Sometimes time is more important... as you probably discovered :-)

Edit: Better yet, get a cheapie on gumtree to tide you over. Lots of welding machines for sale over there usually, sometimes even the odd mig welder too.

Found same type on Junkmail for R899, just a 140Amp instead of 180Amp, but then I'm welding at a much lower amperage anyway.

1 minute ago, plonkster said:

Replace them both.

I'm going to give it a try, hoping Communique is open today.

But I'm also considering buy a as good as new 2nd hand one, it comes with an auto dark helmet, which is quite handy, then sell it as you suggested.

4 minutes ago, Antony said:

I'm going to give it a try, hoping Communique is open today.

Microrobotics in Irene/Centurion area? It's been a few years since I was up there but they are there close by SAAB grintek...

Edited October 20, 20186 yr by plonkster

1 minute ago, plonkster said:

Microrobotics in Irene/Centurion area? It's been a few years since I was up there but they are there close by SAAB grintek...

Perfect, will give them a try, thanks!

https://www.ebay.com/itm/10pcs-FGH40N60SFD-FGH40N60-40N60-Farichild-TO-247-IGBT-600V-40A-/291664260982