Ch 14
Torch will not fire
Prove Mach3 output → relay → plasma connector, then plasma readiness.
Press the physical emergency stop, isolate plasma input power, and do not continue until the output path is proven safe.
Use a dry test whenever a live arc is not required — plasma power off or torch-firing output safely disabled.
Never bypass the emergency stop, limit circuit, charge pump, enclosure interlock, or protective earth to keep production running.
Record the starting condition, make one controlled change, and test again. Restore the original setting if the change did not help.
Symptom
Cycle Start or torch command does not produce a cutting arc.
Quick checks
- ☐Mach3 Reset cleared; correct Premier profile loaded
- ☐UC100 green steady / blue active
- ☐Plasma powered, air present, no front-panel fault
- ☐Work lead clamped to clean metal
Fix
Isolate the chain (safe torch-signal test)
Command torch on briefly and see where the chain breaks:
- Mach3 output does not change → M-code/post, output pin, profile, Reset, macro
- Mach3 changes but relay/contact does not → breakout power, output LED, relay, cable
- Contact closes but plasma silent → plasma faults, cap/torch interlock, air, mode, exact connector manual
- Pilot only, no transfer → work lead, standoff, rust/paint, air, consumables, torch assembly
- Fires from plasma panel but not CNC → CNC trigger path, CNC mode, pinout, profile output
Arc starts then stops
Work lead intermittent; air drops or moisture; worn/mismatched consumables; pierce too high or motion before transfer; speed too high / duty cycle; torch-off in file; limit/comm drop; THC out of range; path crosses gaps in wrong mode.
Still stuck?
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