A Bridge Rectifier Replaced In This Welding Machine Restored It Back To Life
A welding technician brought this machine for repair; and while welding, the machine just stopped working and the earth leakage tripped. He called me right away and after few minutes, he was already at my shop demanding a fast repair. I told him he has to wait till I test it and see what was wrong with it. He was not happy with that but he was willing to wait and see.
The machine was already opened and I headed directly to the bridge rectifier because the customer mentioned something about earth leakage tripping so that was my focus.
Soon enough, when I tested the bridge rectifier, it was shorted and needed a replacement.
Usually they do not come out very easily but this time I used a low melt solder and applied it to the bridge rectifier pins; with hot air using a hot air station, the part was out in no time.
As you can see it was shorted and needed a replacement.
I have plenty of bridge rectifiers in the shop and right away, I cleaned the area with alcohol, applied flux, thermal paste and re soldered it back paying attention to the negative and positive orientation on board. I checked the surrounding area for any defective parts and found none.
Through a current limiter, I powered on the welding machine and I could see right away, the light bulb was dim and the power button lit as expected.
I powered it up again and tested for voltage reading at the negative and positive terminals and as seen, the right voltages were being displayed here. I took it next door for my brother to check and it worked according to specs.
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 Dead Turkish Welding Machine Was Brought Back To Life. Model: Weld-200T
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Parasuraman S
August 12, 2022 at 9:36 pm
Good job, dear friend!
Waleed Rishmawi
August 13, 2022 at 2:00 pm
Parasuraman: thanks man. have a blessed day
Babu M S
August 12, 2022 at 10:24 pm
Master of welding machine repairer is given nice tips to solve the problem.Thank you very much, have a nice day.
Waleed Rishmawi
August 13, 2022 at 2:01 pm
Babu: thanks man. it is a straight foward repair. you are most welcome. have a blessed day.
Albert van Bemmelen
August 12, 2022 at 10:39 pm
Good job! These KBPC bridge rectifiers are well known and I have used several to fix expensive equipment after some power board issues. Like also the KBU1010 1000V 10A bridge rectifiers.
Waleed Rishmawi
August 13, 2022 at 2:05 pm
Albert: thanks man. they are very good but the KBU1010 can not be used in the welding machine because of the low amp rate. rectifiers has to be at least 35 amp and higher. have a good day
Paris Azis
August 13, 2022 at 7:29 pm
Yes,Albert...they are very well known, but also there are plenty of fake ones in the market, sold very cheaply, which one should avoid to buy. Always the spare parts provider must be trustful much more than the brand name of the spare part itself.
Some years ago, I was trying to repair a big linear power supply which my good friend George had it defective for many years. It could (theoretically) put out from zero to 60 volts, up to 20A, all adjustable...
But it was (in my opinion) a bad design. Its power output stage was based on only two 2N3773 transistors, which I consider inadequate for handling such an enormous power output...
So I redesigned the output stage for 9 transistors to share the output current. He had ordered them from an unknown Chinese supplier through eBay...
To my surprise, when testing the current limit function, I had at least one of them shorted!!
After long time spent in order to understand what was going on, I removed the entire heat sink and tried to test it having only one original Toshiba transistor of the same type connected, on the huge heatsink, just for the test. And it turned to be successful! With only one transistor!!
After replacing all of these transistors with the same ones of Toshiba found in the local market, this power supply works since then like a welding machine! No trouble at all.
This was the hardest lesson for me about the good reputation of both the spare parts suppliers and the parts themselves...
Anwar Shiekh
August 14, 2022 at 3:19 am
There seem to be a lot of broken welding machines out your way
Waleed Rishmawi
August 16, 2022 at 7:00 pm
Anwar: yes. a heat wave was hitting our area and seems like a lot of welding machine were over heating causing a lot of damage in these machines. a lot of people called me about how to keep their machine maintained in this kind of weather and I explained a lot to them but some they do not listen so they end up with damaged welding machines. have a blessed day
Lynn Blakely
August 14, 2022 at 4:40 am
good job Waleed:We always enjoy your repairs. You make it sound simple, however you have a lot of experience.
Waleed Rishmawi
August 16, 2022 at 7:01 pm
Lynn: thanks man. I am glad you are enjoying the articles that is such an encouragment to me man. thanks. have a bless day
Waleed Rishmawi
August 20, 2022 at 2:32 pm
Lynn: thanks man. I am glad you like my articles, an encouragement to me and I thank you. it is actually simple to do once you get the hang of it and most of the welding machine are built the same way, just different part choice. have a blessed day
Mathew Charles Karonga
August 18, 2022 at 2:02 am
Good job my friend Waleed Rishmawi well done
Yogesh Panchal
August 19, 2022 at 7:03 pm
Good JOB! Waleed.
Waleed Rishmawi
August 20, 2022 at 2:32 pm
Yogesh: thanks man. have a blessed day