Check the control transformer output groups before blaming the output stage.
Fault route
LGK100L No Output Diagnostic
A two-layer diagnostic route for LGK100L no-output faults, separating control/feedback evidence from power-stage evidence.
Quick Answer
LGK100L no-output diagnosis should be split into an upper control/feedback route and a lower power-output route. Do not replace the IGBT or driver board before confirming control transformer, potentiometer, Hall feedback, fast-recovery diode and filter capacitor evidence.
- Check control-transformer evidence and current potentiometer first.
- Confirm Hall sensor feedback rails before replacing the control board.
- If control evidence is normal, move to fast-recovery diode, filter capacitor, driver indicator and IGBT/inverter evidence.
Use this page when
- Machine powers up but has no cutting output.
- Fan/display/control symptoms exist and output path can be measured.
- You need to decide between control-board, feedback and power-stage faults.
Do not use this page when
- Input breaker trips at power-on.
- The machine is completely dead.
- The only symptom is unstable current under load.
LGK100L no-output route
Two-layer route: control evidence first, output power evidence second.
Open or bad current potentiometer can block expected command behavior.
Check DC15V, -DC15V and signal evidence on the Hall sensor connector.
Disconnect and check diode characteristics if control evidence is not the cause.
Burned or failed filter capacitors can remove output capability.
Use driver-board indicator and visible burn evidence before replacement.
Measurement / evidence table
| Evidence point | Expected / abnormal evidence | Repair direction |
|---|---|---|
| Control-board supply rails | Reference rail groups include 0-27V-36V and 15V-0-15V at the relevant connector. | If missing, inspect control transformer and wiring. |
| Current potentiometer | Open potentiometer or bad contact blocks current command. | Replace potentiometer after confirming wiring. |
| Hall sensor connector | Black-red DC15V, black-blue -DC15V and signal-line behavior are used as source evidence. | If abnormal, inspect Hall sensor and feedback path. |
| Fast-recovery diode | Diode-mode behavior should be checked after disconnecting related leads. | Replace failed diode/module. |
| Filter capacitor | Burned, bulged or failed filter capacitor can cause no output. | Replace failed capacitor section. |
| IGBT and driver board | Driver green indicator and IGBT visual condition are used as evidence, not assumptions. | Replace IGBT/driver only after upstream checks. |