Digital control repair

Digital Welder Control Board Repair Basics

Use this page to separate digital-control faults from power-stage faults before replacing the main board.

What changes in digital welders

Digital welders move many failure points from panel potentiometers and discrete switches into encoders, keys, display boards, MCU/DSP control, Hall current sensors and software-controlled fan logic.

Redrawn digital welder control architecture: input panel, feedback, MCU/DSP, protection and PWM driver.

Redrawn symptom routing map for display, encoder, fan, protection and no-output faults.

Repair split: strong power vs weak control

Layer	Typical parts	Service clue
Power stage	rectifier bridge, IGBT module, 20040 output module	Breaker trip, no OCV, no welding output, power-device short.
Control board	MCU/DSP, isolation, panel interface, PWM command	Parameter cannot adjust, function key dead, display abnormal, no PWM permission.
Feedback	Hall current sensor, voltage feedback, I/V wiring	Display abnormal, current unstable, output too high/low, no output.
Peripheral control	SSR, fan, thermal relay, water-flow switch	Fan does not run, fan cannot stop, protection 804, no HF or HF stuck.