Start at bottom board supply, relay and bridge/DC bus layer.
Board reference
ZX7-160/200 Board Stack Reference
A board-stack service reference for ZX7-160/200 small inverter stick welders.
Quick Answer
This board-stack reference converts the ZX7-160/200 physical board layers into service functions: input/DC bus, inverter drive, transformer/output, feedback and protection.
- Use it when you can see the board layer but need to know what symptoms it can explain.
- Bottom-board faults often look like no control power, relay/start failure or DC bus abnormality.
- Middle-board faults often appear as no output, weak current, thermal/protection or feedback errors.
Use this page when
- You are repairing a ZX7-160/200 style small inverter MMA welder.
- The board stack is physically visible.
- You need to decide which board layer to inspect first.
Do not use this page when
- The machine is a large 3-phase module welder.
- You need a full PCB schematic.
- You are not qualified to access charged capacitors.
ZX7-160/200 board-stack evidence
| Board area | Likely parts / connectors | Faults it can explain |
|---|---|---|
| Bottom board | DC bus electrolytic capacitors, 24 V socket, power relay, start resistor, silicon bridge socket, demagnetizing resistor. | Dead machine, relay click/no click, no auxiliary supply, DC bus abnormal, input-start problems. |
| Middle board | Reactor, feedback wire socket, shunt, thermal switch, main transformer, output rectifier diodes. | No output, weak current, protection after start, feedback mismatch, thermal shutdown. |
| Top inverter board | MOSFET / field-effect tubes, driver transformer, control module, power indicator, bottom-board supply input. | Power-device short, no switching, drive transformer faults, power indicator but no output. |
Repair direction by symptom
Avoid replacing the whole stack before separating function layers.
Inspect top inverter power devices and DC bus short path.
Check driver permission, main transformer, output diodes and feedback line.
Check reactor, shunt, output path and feedback connection.
Check thermal switch, feedback path and power-device short evidence.
Next pages
Move to a deeper record after this board split.