Acdc inverter TIG - second hand or new?

[Sapre]

Im looking at two acdc inverter based tigs;
A jasic tig200, about 2 years old, with few issues consumables for £800 (possibly negotiable)

Or a parweld ttx212di for about £850 new (a good price i think!)

I think the jasic is a better brand, better built? But im also worries that being inverter based, if it goes pop then thats it… given the prices, my gut tells me to go for for the new one… views?

Also how likely are modern machines to just blow (mosfets or other key electronics)? And if they do, are there reasonable service options available?

 

[minimutly]

They do blow. you have to keep them clean and dry, and even then they blow. Could you repair the Jasic?
If the answer is yes then that would be my choice. Anything you can't repair is a gamble, I paid £700 for my acdc tig, and dread switching it on - not a nice place to be...

 

[Sapre]

Thanks thats helpful, i dont want the worry of it blowing!

I wouldnt mind having a go at repairing one but only if it cost me £50, not £700!

Gave me an idea, maybe i’ll have a go at a broken one, ‘spares n repairs’.

Mosfets, fuses what else would blow?
Also a transformer based one would be simpler i guess… dont know how to test these parts (yet) but i know their basic operation, especially for an analogue controlled one..

 

[eddie49]

Mosfets, fuses what else would blow?

The only fuse tends to be the one in the 13A plug, and it may blow due to a shorted power semiconductor ( MOSFET or IGBT ) in the inverter.
One problem is that as a transistor shorts internally, it can send 300-plus volts down the gate connection, which then damages the control logic. A new replacement transistor may then be blown again due to incorrect gate control. For hints and anecdotes, search for "inverter repair" on this Forum.

 

[jo1010]

Go with parweld unless you can find an rtech with the balance of 5 yr warranty still in place...the risk of unknowns is too great otherwise

 

[Sapre]

The only fuse tends to be the one in the 13A plug, and it may blow due to a shorted power semiconductor ( MOSFET or IGBT ) in the inverter.
One problem is that as a transistor shorts internally, it can send 300-plus volts down the gate connection, which then damages the control logic. A new replacement transistor may then be blown again due to incorrect gate control. For hints and anecdotes, search for "inverter repair" on this Forum.

This is helpful, if the whole board is blown, then it will be an expenaive experiment! Thanks for the tips, will search on the forum. Im buying it now so lets see, best case i get a worling machine, more likely scenario, i have a poke around and learn about power electronics and salvage some parts to use/ add to my heap

 

[Sapre]

Go with parweld unless you can find an rtech with the balance of 5 yr warranty still in place...the risk of unknowns is too great otherwise

If my repair doesnt work (quite likely), i’ll do this. I came to same conclusion myself, wouldnt risk 7-800£ for an inverter machine without a guarantee..

Cheers