A Welding Machine With Overheating Issue Repaired
A welding technician brought in this welding machine for repair. It is a different kind of welding machine but still good brand and a good quality device.
I have worked on this kind of model before so it should be an easy repair. When I powered on the device right away I got a warning light which is an indication of overheating which means shorted parts on board.
Usually when I get the overheating light, the machine would not even start; it is kind of a way of how the machine is protecting itself from further damage. From experience when getting such warning it is usually the IGBT/Mosfet shorted out in the device.
Few screws out and I was able to take the top cover off exposing the inside board. In this machine there are two boards, one in the bottom and one on the top.
That is the top board which controls the display and the amp variable resistor; in other words the amp potentiometer.
Once the top board was disconnected from the machine and I took the main board out it was time now to check for shorted parts.
I took one of the IGBT’s out and tested and it was shorted.
I checked the SMD parts around that part and found everything to be ok.
The part number is GW40V60DF and from experience, if one is shorted there will be one on the other side of the board shorted as well and that is exactly what I found.
Click here to access the GW40V60DF Datasheet
I usually replace the four IGBT’s here but when I called the customer he did not want to pay the full amount for repair and he wanted only the faulty ones to be replaced. I tried to explain that it is better to replace all of them but he insisted on replacing only the faulty ones and that is exactly what I did.
I replaced the faulty ones as see in the photo and soldered them on board. Before powering on the machine I checked around the second IGBT for faulty SMD components and found all of them to be ok.
Through a current limiter I powered on the machine and as seen it powered on just fine and the overheating indicator was off and that was pleasant to see.
I powered the machine normally and got reading on the output terminals of the machine and that is a very good reading. I took it next door to my brother to check the machine and he gave me the thumps up and that put a smile on my face.
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 article on A TV With Faulty Backlight Repaired And Maintained
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Anwar Yunas Shiekh
September 30, 2023 at 9:08 am
Surprised he didn't let you replace the whole group.
Waleed Rishmawi
September 30, 2023 at 11:08 am
Anwar:the cost of parts is very expensive and not many welding techs can not afford it. The machine is still up and running because he brought to me to replace the power key and he is still happy with it. Have a blessed day.
Albert van Bemmelen
September 30, 2023 at 4:30 pm
In the event the other 2 still good IGBT's do get shorted in the near future the customer no doubt still will have to pay for an even costlier repair!
But you did warn him and he refused that option. That is probably also because you told him that 2 IGBT's still were okay, which you for his sake maybe shouldn't have told him? By replacing all 4 of them for the higher price.
Like we also replace all diodes in a diode bridge when not all diodes were defect as a precaution. Especially when a high voltage surge was the reason.
Waleed Rishmawi
October 2, 2023 at 2:23 pm
Albert: I am obligated to tell him about what is going on in his machine. He refused my recommendation and therefore it is his fault. on the other side, his machine is still up and running because last time the same machine showed up to my shop for power button replacement. have a blessed day
Parasuraman S
September 30, 2023 at 5:35 pm
Strange are the customers with different backgrounds! Good fix and timely too!
Waleed Rishmawi
October 2, 2023 at 2:24 pm
Parasuraman: yes indeed, customers are different and based on that we get different response from them about repair. have a blessed day and thanks for your comment
Imoudu.O
October 1, 2023 at 11:01 pm
Some customer always think we want to get more money from them even when we tell them the TRUTH.It's profitable to say the truth to them because at the end it plays out to our advantage in terms of customer turnover and God's fear.
Waleed Rishmawi
October 2, 2023 at 2:26 pm
Imoudu: I am obligated to tell the truth to the customer and whatever he wants to be done I do even though I give him my recommendations what to do and if he resused it is his fault not mine. have a blessed day
Yogesh Panchal
October 5, 2023 at 12:34 am
Good Job! Waleed,
There is no value to our recommendation to the customer where extra price is involved.Because most of them are don't care for your Time /effort involved in repair.