What maybe causing this Chopper to short ?

[SM-Piyes90]

Re: What maybe causing this Chopper to short ?

Hi again am back on topic again .

I just want to point out the solution for my original problem with the welder

I have used original IGBTs from fairchild and they have worked without getting shorted , i guess i was using counterfeit components ( big mistake ) .

[Agent24]

Re: What maybe causing this Chopper to short ?

Yeah, that would do it. Power transistors are very often fake from China (Usually they use a lower-rated part and relabel it)

[ben7]

Re: What maybe causing this Chopper to short ?

Great page on fake transistors!
http://sound.westhost.com/fake/counterfeit-p2.htm

Usually the silicon die is too small, and can't handle the power that the bigger ones can. Sometimes the labeling looks strange.

[stj]

Re: What maybe causing this Chopper to short ?

did you check the flyback transformer?

[Agent24]

Re: What maybe causing this Chopper to short ?

This might help you: http://www.repairfaq.org/samnew/tvfaq/tvhorkboeh.htm

Also check through the whole document for general CRT TV information http://www.repairfaq.org/samnew/tvfaq.htm