Magnum MIG 200 MMA J: Transformer Burned, Wire Feeds Without Trigger

Hello, yesterday, during welding, the flicker stopped welding, only the green LED glows, and as soon as it connects to the power supply, it pushes the wire immediately, even if the gun is not pressed. After removing the housing from one plate it smells of burning, and more precisely from this yellow transformer, maybe someone knows what to replace and where to look for parts?
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Where do you store the migomat? You can clearly see traces of water on the tile (white spots) and that's where I would look ...

The Migomat has always been in the garage but has recently been stored in the barn but it is dry there

Unlocked at the request of the author.

Hello Migomat, I was able to repair by buying a second PCB, I found a guest who is difficult to sell migomats and parts via the Internet, but the PCB cost me PLN 390, I bought it because I needed it, but by the way, I returned the old PCB to an electrician and he managed to repair it cost was PLN 150

@piotrek_brt the repairman gave the cause of the failure and what did he replace?

Magister_123 wrote:

@piotrek_brt the repairman gave the cause of the failure and what did he replace?

No, but I can find out

piotrek_brt wrote:

Hello Migomat, I was able to repair by buying a second PCB, I found a guest who is difficult to sell migomats and parts via the Internet, but the PCB cost me PLN 390, I bought it because I needed it, but by the way, I returned the old PCB to an electrician and he managed to repair it cost was PLN 150

Hi
can you give me a contalt on oprave?

Did you maybe find out? I have the same

There was probably damage in the wire feed regulation circuit, in order to find out what is damaged, measurements must be made

I do not have contact with this electrician anymore, but the replacement of this plate or repair has helped migomat so far it welds nicely but first try to remove this plate and take it to an electrician, let him check it, unless I open my own and see where it was soldered

master250 wrote:

to find out what is damaged, you need to take measurements

Yes, necessarily. Only what?


The fault in these Chinese is standard - a short mosfet transistor keying the feeder power supply - https://www.elektroda.pl/rtvforum/topic3396853.html

Hello, I recently burned such a migrate and initially the inverter turned out to be a defect, the keying transistor was burnt ... But after the replacement, the flash fired, the display lit up, but after a while it went out and started to freak out with the feeder ... So I replaced both motor drive transistors but after restarting it again for a moment, then after a few seconds the same symptom ... It turns out that these transistors are burning ... I checked the elements from this area on the board, but none of them show signs of piercing ... Before them all of them will start to desolder, maybe one of you will tell you what could be the reason? I will be very grateful for any help

PS In the diagrams I see differences in the use of these mosfets, on the P channel they use IRF9z24 and IRF9540, I inserted the IRF9540 (someone has already repaired it and walked on IRF9640)
In turn, on the N channel IRFZ44, (he was on IRF640) I put IRF540



FIXED!

So, in my case, the converter fell, i.e. practically all the elements on it:
VT3 - 2SK3878 (there is one in my version)
U3 - UC3842
U4 - PC817
R48 - 10R
R50 - 10K
R51 - 1R
R52 - 1R
R57 - 1R

When repairing it, I forgot to replace the U3 Optocoupler, which caused me a lot of blood ... As a result, there was a double voltage at the output of the transformer and the rest of the elements were burning, mainly the transistor from the wire feeder, and then the capacitors exploded ...
I hope someone will find my experience useful