Replacing Open SMD And Shorted IGBT’s Restored This Welding Machine Back To Life
A shop owner nearby brought this dead welding machine for repair and as he explained the fault I came to realize this Apex welding machine all have the same fault and I was almost sure that I will see the same exact blown parts I saw in many Apex brand machines.
Usually when IBGT’s or SMD parts are open/ shorted in this kind of machines, it does not power on so I did not bother with that but headed directly to the faulty area.
If you look to the photo, there are no faulty parts obviously seen but as I get closer through a magnifying glass I was able to see the open SMD resistors there. Also the IGBT’s on that machine were also shorted and there are four of them there.
There are three IGBT’s shorted and 2 SMD resistors marked 100 which means the value of them are 10 ohms each were open. The plan was to replace the four IGBT’s along with the open resistors so I called the guy who brought this welding machine for repair and explained the situation. The guy said he will call the customer and return back to me to confirm the price so I can begin the repair.
After two weeks of waiting, finally I got the call to start with the repair so first thing to do was to take the shorted IGBT’s and replace them with good new ones.
There were three shorted ones but I replaced the four of them any way with the same exact part number which is 40N60NPFD.
Click here to access the 40N60NPFD Datasheet
I also replaced the two open resistors with same value of 10 ohms each. Before powering on the welding machine, I checked to see other shorted or other open resistors and as expected there were none.
One thing left to do before powering on the machine. I set my multi meter to ohm setting, checked the outside pins of the IGBT’s ( while soldered on board) and made sure all have the same resistance value and if the values are not the same something is still wrong in that area or there are cold soldering joints not making good connection to give the same exact ohm reading. All checked OK.
I connected the welding machine to a current limiter and powered it on. The light was dim which indicated that all was well to power it on with a normal 220 AC volts.
I gave it to my brother next door to give it a try; the outcome was as expected.
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 Welding Machine Powers On But Does Not Weld Repaired. Model: INC-CO
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Parasuraman S
December 2, 2023 at 12:58 pm
Another professional fix from an expert! Many thanks for sharing! You are lucky to have a brother nearby, who can do the testing!
Waleed Rishmawi
December 6, 2023 at 6:05 pm
Parasuraman: thanks man for the kind remarks. yes my brother always help in testing the machines and make sure it they are working the way they should be. have a blessed day
Albert van Bemmelen
December 2, 2023 at 4:27 pm
The many power hungry machines you already were able to fix is quite extraordinary!
Waleed Rishmawi
December 6, 2023 at 6:16 pm
Albert: thanks man for your kind remarks. I do what I can to help out. have a blessed day
Yogesh Panchal
December 2, 2023 at 10:16 pm
Sometime hairline crack or dry solders only visible in magnifying,
Microscope is the best equipment for fault finding.
Waleed Rishmawi
December 6, 2023 at 6:17 pm
Yogesh: yes I invested in an expensive microscope and it is working greatly for me. have a blessed day
Babu M S
December 2, 2023 at 11:24 pm
Many many thanks to sharing such a welding machine problems.
Waleed Rishmawi
December 6, 2023 at 6:18 pm
Babu: you are most welcome. have a blessed day
Imoudu.O
December 3, 2023 at 1:29 am
Good fix friend!
Waleed Rishmawi
December 6, 2023 at 6:18 pm
Imoudu: thanks man. have a blessed day
Okori Andrew
December 4, 2023 at 1:40 am
Why use the ohms setting to check the outside pins of the IGBT's but not the diode setting. Andrew Okori
Waleed Rishmawi
December 6, 2023 at 6:20 pm
Okori: for me, ohm settings is more accurate for me since I can check the ohm resistance in that area. have a blessed day
Mendis
December 18, 2023 at 8:52 pm
Good job and nicely explain