Diagnostic tool
Auxiliary Power Rail Checker
Enter measured control-power rails to identify likely regulator-chain sections before diagnosing PWM, driver or protection circuits.
Enter measured DC rails
Rail analysis will appear here
Enter measured values. Leave unknown rails blank.
Default reference bands used by this tool
The first version uses practical reference bands around common ZX7-type control rails. Future WelderData board records can add model-specific test-point limits.
| Rail | Expected practical band | Typical section |
|---|---|---|
| +25V / -25V raw | Approximately 20V to 30V magnitude | Control transformer / rectifier / filter before regulators |
| +15V | 13.5V to 16.5V | 7815 regulator and positive analog / driver supply |
| -15V | -13.5V to -16.5V | 7915 regulator and negative analog supply |
| +5V | 4.75V to 5.25V | 7805 logic / control IC supply |
Inverter TIG rail and protection note
For TIG inverter control boards, a visible 24V load such as a fan, relay or display does not prove that the driver and control rails are healthy. If 24V is present but PWM remains disabled, check the 20V driver rail, the 15V IC/control rail and protection inputs before replacing the PWM IC.
WelderData uses TIG protection references such as 260V-class mains overvoltage, 160V-class mains undervoltage, low 20V driver-rail behavior and heatsink thermal shutdown as routing clues. Always confirm the actual board family and test-point references before making final repair decisions.
Related pages
ZX7-250 auxiliary rail note
Some ZX7-250 power-board layouts provide positive and negative raw auxiliary rails before the downstream regulator chain. In practical diagnosis, do not jump from a missing +5V rail directly to the PWM chip. First confirm the upstream raw rails, then the +15V / -15V stages, and only then the 5V logic supply.
Current-display caution
A signal board can show a changing current value when powered from a safe external 24V bench supply. That behavior helps confirm board activity, but it does not prove real welding current. Use the Current Display vs Shunt Check Tool when a panel value must be compared with a shunt measurement.