Diagnostic tool
Current Display vs Shunt Check Tool
Estimate real output current from a shunt measurement and compare it with a panel current display before judging current feedback or output-stage faults.
Enter shunt and panel readings
Result will appear here
Enter shunt values and generate a real-current estimate.
How this WelderData tool should be used
This tool is a service calculator for comparing a panel display value with an external shunt measurement. It does not replace a safe load test, calibrated meter or qualified repair procedure.
If the panel display changes under a 24V signal-board bench test but the shunt shows no output current, the panel value should be treated as a simulated control-side value, not real welding output.
A low-current post-repair welding test may show a real output current far below the machine rating. In one WelderData ZX7-250 validation pattern, a 300A-class external meter was used during a light-load test and the actual current was about 50A. That type of external-current evidence is more useful than relying only on the front-panel number.
Calibration reference link
If the shunt-estimated output current and panel display do not agree, avoid immediately adjusting the display. First confirm the current-command path, feedback zero and board-family shunt reference. WelderData separates W4 maximum display, W8/W7 minimum display, W7 feedback zero, W6 shunt signal and W5 200A display alignment as separate service checks.
Panasonic RF2 meter and shunt service notes
Some inverter CO2 platforms use meter scaling checks that should be recorded separately from arc behavior. Panasonic RF2-style service evidence includes meter full-scale accuracy within about 2.5%, current meter zero alignment with no output current, and a 60mV-class full-scale meter/shunt reference.
| Meter evidence | What to check | Repair note |
|---|---|---|
| Current meter at zero output | Display should return to zero when no welding current flows. | A non-zero display can be display scaling, feedback offset or meter wiring. |
| Full-scale current meter reference | Check for a 60mV-class full-scale meter/shunt signal where applicable. | Do not adjust the display before confirming the actual shunt or CT evidence. |
| Clamp meter comparison | Compare panel current with a calibrated clamp meter or external current measurement. | Panel current is a service indication, not the final proof of arc current. |
| Voltage display | RF2-style voltage display reads output-terminal voltage. | Output-terminal voltage is not always the same as true arc voltage at the workpiece. |
| External display wiring | Use short wiring and adequate conductor size for external display/signal terminals. | Long signal leads can introduce voltage drop and noise pickup. |
For RF2-specific fault routing, compare this tool with the RF2 E-code and wire-feed/gas routing pages.