Welder not turning on - Learning
Hello people. I trying to repair my welding machine oerlikon citomig 180mp hpf and there is a little board with blown stuff.The problem is i cant identify the value of the blown resistor and diode. Any suggestion?
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I guess you got 2 choices.
A: Replace the board as a whole
B: Maybe you are lucky and find the datasheet from that 8pin DIP IC (gate drive) and see what the example circuit has to offer.
Chances are you going to need that IC anyway, since the Mosfet blew and shorted to the gate drive. -
The 8pin IC is UC3843BN. And yeah the mosfet is shorted source to gate.Comment
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The worst thing is the company went bankrupt and there is no more spare parts.Comment
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Pin 6 is VCC so that bigger resistor can’t be that high in value. Pin 7 is the destroyed gate drive with the smaller resistor and diode. The diode isn’t that critical but the gate drive resistor doesn’t have to be bang on, but should be as close as we can get it.
What was the mosfet? Upload a straight shot picture of the board from top.Comment
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I removed the heat sink and the mosfet so u can see more and also tried to clear the gunk. I can write a diagram if you want me to.
Note: D201 is also blown and from bottom side R209 too.Attached FilesComment
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almost forgot the mosfet is K3878
Attached FilesComment
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The gate drive resistor is usually something between 0 and 100ohm, the gate drive diode is probably something similar as an RB160L60. The diodes trough hole I'd put something 1A, 600V or better ultra fast in there. The gate resistor and the diode are there to slow the Mosfet down and prevent ringing.
As for R209, I am not sure where it goes to what pin in the IC.
Drawing a supporting schematic would simplify things for sure.Comment
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I just pulled the sales flyer for it and it has Lincoln Electric on the bottom of it. So you should be able to get a spare board as that company shouldn't be bankrupt.
Try these guys in Slovakia :
AIR LIQUIDE WELDING CENTRAL EUROPE S.R.O.
Hlohovecká 6 - 951 41 NITRA - LUŽIANKY
Tel.: +421 37 692 4610 - Fax: +421 37 651 28 04
https://www.wecs-ltd.co.uk/wp-conten...erlikon_en.pdfComment
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already tried but its closed and there is other company
Air Liquide Welding Ltd. - Google MapsComment
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i already working on the schematic i need one more day to finish it
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Very good!Comment
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Let me know please if its readable. Thank you
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I need somehow to guess the values of : R209 , R208 , R207 , D203.
And replacement for : D201 , i found this diode was BYV26EComment
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It is starting to make a bit of sense now how this works. Good drawing! Here is with what I roughly came up with. I am not sure on the exact value of R209 and R207. The BYV26E is better than the 1n4937 that I guessed on D201.
example circuits show R207 as 10k Ohm… as 10R0?Attached FilesLast edited by CapLeaker; 05-19-2024, 05:34 PM.Comment
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