ESAB Plasmarc EPP-450 - Premature Power Supply Shutdown; Unstable or Drifting Output Current

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SECTION 6 TROUBLESHOOTING
Problem Possible Cause Action
Power Supply turns o prema-
turelyinthemiddleofthecut.
“ContactorOn”signalisremovedfromunit.
PowersourceisOK.Troubleshootpro-
cesscontroller.
Momentarylossofprimaryinputpower.
Restore and maintain input voltage
within±10%ofnominal.
Faulty condition, indicated by illumination
ofthefaultlamp.
RemovecontrolPCB(PCB1)accesspanel
todeterminethefaultcausingtheshut-
down.Refertofaultlightillumination
section.
Faultycondition,indicatedbytheillumination
ofthepowerresetfaultlamp.
RemovecontrolPCB(PCB1)accesspanel
todeterminethefaultcausingtheshut-
down.Refertofaultlightillumination
section.
Currentsettingtoolow. Increasecurrentsetting
Remotecurrentsignalremovedduringcut. Fixremotecurrentsignal
Problem Possible Cause Action
Output current is unstable and
drifts above or below the set-
ting.
PlacethePANEL/REMOTEswitchinthe“PANEL”
position.Adjustcurrentcontrolpot.Ifcurrent
nolongerdrifts,theremotecurrentcontrol
signalisfaulty.
Fixtheremotecurrentcontrolsignalto
operatethePANEL/REMOTEswitchin
the“PANEL”position.
Select“PANEL”onthePANEL/REMOTEswitch
andadjustthecurrentcontrolpot.Thecur-
rentstilldrifts,measurethecurrentreference
signalatTB1-4(+)andTB1-5(-).Ifthesignal
drifts,thecurrentcontrolpotisfaulty.Ifthe
signaldoesnotdrift,theControlPCB(PCB1)
isfaulty.
Replacethecurrentcontrolpot.
Replace the control PCB (PCB1)  P/N
0558038312