KL MMA160 inverter igbt arc welding machine does not weld although it gives an appropriate value of 52 output voltage

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Joined Aug 6, 2022
The output of the KL MMA 160 inverter igbt arc welding machine is 52 Volts and as it should be.

The fan is also working.

4 High-Speed Switching Diodes (1N 4148 5T) diodes exploded on the Transformer Rectifier circuit card of the machine, I replaced them with new ones, but it still does not weld.

It still only sparks when the electrode hits the metal, but it doesn't weld. The same problem persists when I increase the amps by turning the potentiometer up.

All elements on the AC rectifier curciut card of the machine are solid, namely capacitors and the resistors connected to them, diodes, relay, optocoupler, NTC and PTC.

The rectifier diodes(Output diodes) and IGBTs are also solid.

Since I couldn't understand what the problem was in the machine, I checked all the elements one by one.

I could not understand the reason why the machine does not weld when there is no problem in the cooling fan part, additionally the output voltage of the machine is correct (at a constant value and between 50 V -70 V at the required voltage).

In general, in which part of the machine and in which electronic components should I look for and error considering all this situation?

The diodes I changed are on the Transformer Rectifier circuit card:


Pictures of the machine: