welding machine oc light problem

Switch off and unplug the welding machine, check for overheating, blocked ventilation, loose connections, and shorted welding leads; if the OC light persists, have a qualified technician inspect the inverter or IGBT circuit.

@azarudeendeen verify that your welder is a Toshweld ARC 200.

Regardless of what model this is, in general OC means Over Current. That means a protection circuit has been activated. This is a thermal limit condition and after 10 minutes of cooling down the light should go out. If the light comes on immediately then there is a blown component in the welder.
WARNING: Unplug the machine first and wait at least 15 minutes before opening the case or properly discharge the capacitors before working on this welder.. The large capacitors inside hold enough charge to cause serious injury or death!
With a multimeter in continuity mode, test the positive and negative terminals on the front panel of the machine for a short. If they are shorted, then the output diodes are shorted. If the front terminals test good then you will have to open the case. There is a row of large black transistors (IGBTs or MOSFETs) bolted to the aluminum heatsinks on the right side of the machine. Test the legs of every single one of them. If any of them read a dead short then that IC has failed and is tripping the circuit.

Post some well focused pictures of what your circuit boards and wiring look like when you remove the out case. That way we can see what you see and hopefully help you further. iFixitでの質問に画像を追加する方法