The problem is intermittent. When I turn the machine ON, the cooling fan runs, but the digital display does not turn on and the green power LED does not light up. There is also no welding output.

The power switch has been checked and it is working correctly. When the power switch is ON, the fan runs. When the power switch is OFF, the fan stops.

Previously, the same problem occurred. The next day I turned the machine ON again and it worked normally: the display came on, the green power light came on, and the welding output worked. Later, the same fault returned and now the fan runs but the display, power light and welding output do not work.

The machine specifications are:
Model: ARC-200
Input: 220/230V, 1 phase, 50/60Hz
Rated output: 200A
No-load voltage (Vo): 62V
Duty cycle: 60%

I want to troubleshoot and repair this machine step by step. Please help me identify which section I should check first. In particular, I would like to know where the auxiliary/control power supply for the digital display, green power LED and welding control circuit comes from after the main power switch.

I have a basic electrical tester and screwdrivers, but I currently do not have a digital multimeter with test leads.

I can provide photos of the machine and PCB if needed.

⟐ Commented Ağustos 26, 2026 at 6:12 GMT-7