A Welding Machine With Warning Light Repaired And Maintained
One of my regular customers brought this welding machine with warning light on for repair. He said the machine powers on fine but it does not weld which is one of the most common welding machine faults.
I have seen this kind of welding machines before and it should be a straight forward fault repair.
What do I mean by the warning light on? It means that there are shorted components in the machine causing the feedback circuit to shut down the welding process to protect it from further damage. It powers on just fine but it does not weld which means ones or more Mosfets are shorted out and need replacement.
Every three Mosfets are in group with one another which means one shorted Mosfet will affect the rest of the group. The only way to find which Mosfet is shorted out is by de soldering it off board and be checked alone. Here I located the shorted group of Mosfets and it is time take every part out to be checked and verified if ok or not.
In this case one Mosfet was shorted out; I usually replace the whole group but the customer wanted only one to be replaced because he thought it is beyond his budget range and to that agreement I acted it out on this repair. The part number is K2837.
Click here to access the K2837 datasheet
The previous photos show more fault to be taken care of.
An open 10 ohm resistor along side of the shorted Mosfet, a broken electrical socket, Mosfet and the power switch were all replace because they were not in the best conditions.
I put everything back together and tested the machine at my brother’s workshop next door and it was working according to specs. I called the customer for pick up but he did not show up to my shop till a week after due to shooting going on in his area.
The customer tested the machine himself outside my shop but sorry I was not allowed to take photos; the customer was happy with the outcome but tried to bargain about the repair cost. I told him a deal is deal because we discussed it before and he agreed to it.
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 An Easy Fix To A Dead HP Computer Monitor
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Albert van Bemmelen
May 4, 2024 at 8:53 pm
The customer probably argued about the now also replaced powerswitch and AC power cord?
But without those it of course will never work. A deal is a deal and fair is fair.
Waleed Rishmawi
May 6, 2024 at 4:36 pm
Albert: yes indeed. since we are living in a war situation I am getting this the whole time but not all people are like that..have a blessed day
Anwar Yunas Shiekh
May 4, 2024 at 9:57 pm
Once agreed, hagging is over.
Waleed Rishmawi
May 6, 2024 at 4:37 pm
Anwar: yes indeed but people are not learning that lesson. have a blessed day
Parasuraman S
May 4, 2024 at 10:19 pm
Good that you too gave him a shot from your side so that such customers learn a lesson! Many thanks for sharing, dear friend!
Waleed Rishmawi
May 6, 2024 at 4:39 pm
Parasuraman: you are most welcome my friend. people still have not learned that lesson yet and being in a war situation is making it hard to accept such lessosn. have a blessed day
Yogesh Panchal
May 5, 2024 at 12:35 am
Good job! Waleed.,
Power plug look like for 5 Amp??
Waleed Rishmawi
May 6, 2024 at 4:40 pm
Yogesh: no power plug is rate at 16 amps otherwise it would be melting in no time. have a blessed day
Michael Gallegos
May 5, 2024 at 1:09 am
Glad to hear you received the agreed upon payment, that’s always an uncomfortable situation. Out of curiosity, did you find the shorted MOSFET using the diode test function of a DMM or a test circuit for MOSFET’s?
Thanks for the article and info!
Waleed Rishmawi
May 6, 2024 at 4:45 pm
Michael: you are most welcome.
you can use either way to find out the shorted mosfets. in this case I used a diode function testing because it was very obvious where the short was but if not obvious I could test it through the main board where all the mosfets connects and that would tell me where to look for. have a blessed day
Alford Myers
May 5, 2024 at 3:28 am
Hi Waleed,
At my shop I Service theatrical electronic equipment,electronic musical instruments And amplifiers.
One of my customers brought in a similar welder with the same issues. Because I have read many of your articles on Welder Repair. I was able to easily identify and repair the problem.
I literally told the customer I’ve read a few articles on it… Which was absolutely the truth and they all have been your articles. Thanks for covering your Repair technique so well And sharing what you know!
Waleed Rishmawi
May 6, 2024 at 4:47 pm
Alford: that put a simle on my face when I read that. thanks for the ecouragement that people are learning and gaining experience out of these articles. have a blessed day my friend and keep up the good work.