A man who is in the business of installing signs brought his welding machine for repair. It was on but there were no voltage reading at the output of the machine. I have seen this fault before on other machines so I headed for the expected faulty area.

This is a Zika that is well known for its quality and durability. It is complicated to repair for as you can see, the power board has too many wires connected everywhere.

They are just hard to follow and it is so difficult to take the power board out of the machine.

The Zika welding machine all use Mosfets with part number 23N50 and they are very expensive to buy but lucky me I found the same part number, very cheap on line so I bought tones of them.

Please click on the above photo to view the 23N50 datasheet

As expected, one of  was shorted and needed replacement but to my shock after replaced the shorted Mosfets, the machine warning orange light was off and I got voltages out. The moment I tested the machine for welding, the voltages drops down to almost 20 volts which not enough to do the welding.

So that is a new learning experience for me because when I get voltages out the machine should work but in this case, it was not working which indicates other fault in the machine.

And the question here is what is causing the welding voltages to drop during the welding process.

I checked all capacitors and they all checked fine but when I looked for bad and cold soldering joints I found plenty especially near the Mosfets area. I re soldered the joints one by one on the power board which felt that it took me forever to do.

Finally, after all the soldering was done. I checked the voltages again and guess what, they were higher than before. The first voltage reading was around 83 volts but with Zika machine (learned that recently) that it needs at least 100 voltages at the out of the machines.

As you can see, the voltages were over 100 and when I did the welding, the machine did a marvelous job and kept going for a while. That put a smile on my face because I have learned a new thing today and the machine is up and running and nothing can beat that.

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/a-dead-hovering-board-power-supply-was-brought-back-to-life