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Bench evidence

Welding Machine Component Testing Guide

A practical component-testing route for welding-machine repair. The diagrams are code-redrawn SVGs, not scanned page images.

Code-redrawn diagrams only

This page no longer uses scanned page images. All component figures are redrawn as lightweight SVG diagrams with English labels. Detailed procedures are carried in searchable HTML tables.

Use a staged evidence stack before replacing power semiconductors.
Use a staged evidence stack before replacing power semiconductors.
Diode forward and reverse test with English meter-lead labels.
Diode forward and reverse test with English meter-lead labels.
Dual diode module reference redrawn from the service-training logic.
Dual diode module reference redrawn from the service-training logic.
Three-phase rectifier bridge: verify all six internal diode paths.
Three-phase rectifier bridge: verify all six internal diode paths.

Quick decision table

PartNormal evidenceReject evidence
Single diodeConducts in one direction and blocks in the reverse direction.Zero both ways or open both ways.
Dual diode moduleEach internal diode path behaves consistently.Any shorted or open path means the module is not reliable.
Three-phase bridgeAll six AC/DC paths show consistent diode behavior.A shorted path often trips the input breaker immediately.
IGBT moduleGate charge changes C-E behavior; built-in diode remains directional.Permanent C-E short, no response, or uneven parallel branches.
Driver boardAll gate-drive branches are close to the expected resistance values.One branch reads zero, open, or far from the others.
IGBT terminal layout redrawn with Gate, Collector and Emitter labels.
IGBT terminal layout redrawn with Gate, Collector and Emitter labels.
Driver board resistance comparison for four gate-drive branches.
Driver board resistance comparison for four gate-drive branches.

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