A welding technician came to my shop and explained the main problem with this welding machine.  He said, the moment he starts to weld, it worked for a minute or two then it stops.

He did not explain to me the meaning of “it stops”. I have to find out on my own.

Does it mean it stops welding, or the whole machine shuts down? I am not really sure. So I took it to my brother’s welding shop next door and asked him to work on it.  He worked on it for almost five minutes and it stops. That means, it stop welding but the machines was still on and the 55 volts were coming out of the negative and the positive terminals of the machine. The fan was still on and that means it was not an overheating problem.

I took the cover off and looked inside. There was dust covering the surface of that board and it had to be cleaned.

It is always a good idea to blow the dust away. It helps me to see if there are cold or loose soldering joints or any broken traces.

Note the difference between the two photos? From experience, a problem like that usually is a result of cold joints or loose soldering around the parts. That was my main focus with this repair.

That was my first finding. The first joint on the left side of the photo is the worse one. So I had to re solder all the three pins.

 That is my second findings and that was the worst. I had to re solder that as well. I did a detailed check of all the soldering joints on this machines and it seems like these only two were the main problem.

Once I took the machine back together, again, I took it back to my brother and he did some welding on it. This time, it kept working like a charm. Another thing I noticed is the welding cables. Look how nasty there are.

I gave a strong recommendation to the welding technician to replace all these bad welding cables. He agreed. Mission Accomplished.

This article was prepared for you by Waleed Rishmawi, one of our ‘Master Authors’ and currently working in the Bethlehem area of Palestine repairing electrical and electronic equipment.

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Note: You can check his previous repair articles in the link below:

https://www.electronicsrepairfaq.com/safety-locks-on-a-microwave-oven-replaced-model-lg