Shorted IGBT In A Welding Machine Replaced
A welding technician brought this welding machine for repair. As I understood it from the guy, the machine was welding fine then it went into shut down. He tried to connect it to a different power source but was no use.
The customer also made a remark that the Overheat light indicator was going on and off and then it went into shut down.
That was a good remark and based on that, I headed directly to the IGBT and I am almost sure there lays the problem.
I tested for short there and as expected, the meter indicated a short in the area of the IGBT and based on that I took the first heat sink out for further testing.
The main power switch has to be taken out as well so I can reach the other shorted IGBT there.
Both heat sinks holding the 4 IGBT were taken out and my testing was confirmed.
Two IGBT out of four were shorted but from experience, it is better to replace all four and that is exactly what I did.
Part number FGH60N60
As seen in the previous photo, I replaced all Four with the same exact part number and then powered up the machine. The reading you see on the meter is low because the machine was connected to my current limiter but when connected to power without the current limiter, the reading was almost 60 DC volts. Of course I never give it to the customer without the actual test of welding so I took it next door and gave it to my brother the welder and gave it a try. It was working according to specs.
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 Cheap Bluetooth Speaker With Ripped Charging Ports Repaired