Diagnostic tool
IGBT Replacement Precheck Tool
Generate a WelderData pre-power checklist before installing and validating new IGBTs, MOSFETs or H7B-style power devices in a failed inverter welder.
Check each item before replacement
Precheck report will appear here
Tick the items that have been completed. The tool will flag missing precheck and staged power-up validation steps that can destroy replacement devices or hide a no-output condition.
Why this check matters
A failed IGBT or MOSFET is often the visible result, not the complete root cause. In WelderData power-stage records, repeated device failure usually requires checking the gate-drive branch, primary driver network, output rectifier path, control-power rails and staged power-up condition before a new device is installed.
The expanded checks include the 3846-style PWM output path, the primary-side driver device, the 102 capacitor and the 22Ω resistor path. These parts are upstream of the four isolated gate-drive outputs. If they are damaged or shifted, a replacement tube can fail even when the new tube and the secondary branch parts are good.
A jumping or unstable meter indication at the transformer-primary drive point can be useful evidence. It does not provide a calibrated drive voltage, but it helps separate a completely dead signal board from a board that is producing switching activity.