Model family
Small Inverter Stick Welders
Portable stick welders are compact inverter power sources where the repair path usually begins with input rectification, DC bus safety, MOSFET or IGBT switching devices, high-frequency transformer drive, secondary rectification, feedback and protection behavior.
Database summary
WelderData groups small inverter stick welders as portable MOSFET or IGBT machines that share a common power-conversion structure: rectified mains, high-voltage DC bus, high-frequency switching bridge, transformer, secondary fast rectifier, output inductor and control board. The physical layout can be very different between brands, but the diagnostic order is similar.
This page is not a welding technique guide. It is a repair database hub for separating power-stage shorts, auxiliary supply loss, driver failure, output rectifier faults, fan/display-only symptoms and protection-lock behavior.
WelderData power-flow map
MOSFET versus IGBT field diagnosis
| Area | MOSFET portable inverter | IGBT portable inverter | Repair meaning |
|---|---|---|---|
| Power device failure | Drain-source short and gate damage are common after bus or driver stress. | Collector-emitter short and gate-emitter damage are common after overcurrent or weak drive. | Do not replace the device before checking driver bias, gate resistor, clamp path and snubber parts. |
| Driver behavior | Often discrete transformer or totem-pole drive in older compact machines. | May use transformer drive, opto-driver, hybrid driver or control-board push-pull stage. | Identify the drive family before applying ZX7-specific assumptions. |
| Secondary side | Fast recovery diodes or dual-diode modules can short and load the inverter. | Same output-rectifier risk, often with higher current modules. | Output diode-mode testing belongs before full-power restart. |
| Protection clues | Fan/display may work while PWM is disabled by protection. | Protection lamp or shutdown may be triggered by overcurrent, thermal or feedback abnormality. | Confirm low-voltage rails and protection inputs before judging the main PWM IC. |
Common repair sequence
- Record the symptom: no output, lamp-limiter bright, fan only, protection lamp, weak arc or repeated switch failure.
- Discharge and check the DC bus before resistance or diode-mode testing.
- Separate input rectifier, bus capacitor, switch bank, transformer primary and secondary rectifier paths.
- Verify auxiliary supply and driver bias before installing new MOSFETs or IGBTs.
- Use a staged power-up method: lamp limiter, bus confirmation, open-circuit voltage, then light-load weld test.