A Shorted/Dead Welding Machine Repaired. Model: Apex ACR-180
A welding technician brought many welding machines for repair. This one was urgently needed so I started right away finding the fault in this machine. The technician explained that the machine comes on but does not weld because when I powered it on though a current limiter, the fan came on but the fins on the fan were all broken and based on that I figured right away, we are going to have blown parts inside.
I checked for voltages while the machine was on and as expected, it was dead, no reading whatsoever.
The technician explained that when he was welding, he heard the fan running he did know that the fins are broken therefore no cooling was being done inside.
Obviously, this machine was seen by another technician and he did not do a good job because of the mess that was done here. There are SMD diodes and resistors in this area but they were replaced with normal resistors and not with the same value.
I started the repair here first before heading to replace the blown IGBT on the other side of the machine. I replaced the two resistors on both side and a diode.
The parts replaced here are SS14 diode, 220 and 5.1 ohm SMD resistors. The diode on the other side was ok so no replacement there.
Other the other side of the welding machine is a completely different story, the IGBT 60N60FDI was blown to pieces, the other IGBT with the same part number was no burnt like these but still shorted and needed replacement.
That is one of the replacements for the blown IGBT and of course adding a thermal paste is a must in this situation.
This is the other IGBT which is found on this heat sink; the bridge rectifier was tested and found ok so I did not replace that.
I cleaned the area, added a new IGBT on this side as well and I was about to test when the customer called me to ask if the machine is ready. I told him almost ready because I am about to install a new fan and then will test it out. He told me not to install the fan because he wants to do it himself. I explained that I will not take any responsibility if the parts are blown again and the customer agreed (thinking that he is saving money this way).
In order for me to test the machine, I installed a fan and powered it on using a current limiter device; this time I was able to read some voltage readings here and that is a very good sign.
My brother tested the machine out and it was up and running according to specs. I took the fan out, called the customer for pick up and when he came I made him sign a document that it is his responsibility not mine if the welding machine goes dead due to lack of cooling inside it.
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 Successfully Repaired A Dead Hover Board Charger