Main Bridge Rectifier Shorted…….
A dead welding machine was brought back to life.
A welding technician brought this Turkish made welding machine for repair. It was the only machine he had so he needed it as soon as possible. While the customer waits in the shop, I opened it and tested it out.
The machine was completely dead and there was no sign of life in it except for the power switch that was on.
Sorry it is out of focus photo but you can see the bad shape of these twisted wires.
I thought this was the problem but when I tested the output with the multi meter, I was able to read 220 AC volts there. (cable were not connected to the board).
I started checking components on the power board and looking for shorted parts and guess what? The main bridge rectifier was shorted.
One of the pins of the rectifier “the minus” was shorted to one of the AC pins.
According to the customer, the earth leakage tripped when he was welding but this information I did not get tell after I saw this fault.
I did not have the same part number but I managed to replace it with the same specs. I believe it was 36 amps bridge rectifier.
To de solder the bridge rectifier off board was not an easy task but finally it was out and the replacement was done.
I checked for more shorted parts on that power board but lucky me, there were none.
The bridge rectifier was replaced and the power board was put back inside the machine. I powered on the machine and of course, as expected, the machine was alive again and I confirmed it with these voltage readings at the negative and positive terminals of the welding machine.
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 repair articles in the link below:
https://www.electronicsrepairfaq.com/lithium-polymer-battery-fault-in-blue-tooth-speaker
About admin
Jestine Yong works as an Electronics Repair Lecturer in Kuala Lumpur Malaysia and his training website is http://www.NoahtechElectronicsTraining.com. You can check out his repair blog at http://www.JestineYong.com
7 comments on “Main Bridge Rectifier Shorted…….”
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When I read ‘Welding…’, I know who could be it, an easy guess! Well done!
Parasuraman? thanks man.
Well done!
Albert: thanks man.
I always enjoy reading about your repairs on welding machines in case I ever need to repair my welder. So far the articles have been about simple machines. I think a book on those simple welders would probably sell in the US since there are many inexpensive Chinese welders sold here and the welding repair businesses are aimed at industrial customers rather than the usual buyer of a Chinese welder. For my own purposes I’d like to know how to trouble shoot Miller TIG and MIG welders, which are more complex. Miller is good at providing circuit diagrams.
Robert: I am glad you are enjoying the articles. sad to say in the USA they do not repair Welders according to what I heard from people there since these Chinese made welding machine are cheap and it is better to buy a new one rather than repair.
I have not got into detail about trouble shooting a Miller TIG welders, they are not used that often there because they are expensive and usually come with long warranty period. My brother recently bought one and from what I saw from the schematics, they are a bit complicated but if I come across, I will let you know. have a blessed day
I like your approach… simple, logical, thorough, effective! I am learning and inspired much from you. Thanks.