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38
12. Troubleshooting (electronic models)
12-1 ElectricalMalfunction
PRECAUTION
1.CHECKGROUNDINGBEFORECHECKINGFORTROUBLE.
2.BECAREFULOFTHEHIGHVOLTAGECIRCUIT.
3.DISCHARGETHEHIGHVOLTAGECA PACITOR.
4.WHENCHECKINGTHECONTINUITYOFTHESWITCHESORTRA NSFORMER,DISCONNECT
ONELEADWIREFROMTHESEPARTSANDTHENCHECKCONTINUITYWITHOUTTHE
POWERSOURCEON.TODOOTHERWISEMAYRE SULTINAFALSEREADINGORDAMAGE
TOYOURMETER.
5.DONOTTOUCHANYPARTOFTHECIRCUITORTHECONTROLCIRCUITBOARD,SINCE
STATICDISCHARGEMAYDAMAGEIT.
ALWAYSTOUCHGROUNDWHILEWORK INGONITTODISCHARGEANYSTATICCHA RGE
BUILTUP.
SYMPTOM CAUSE CORRECTIONS
Ovenisdead.
FuseisOK.
Nodisplayandnooperationatall.
1.Openorlooseleadwireharness
2.Openthermalcutout(Magnetron)
3.Openlowvoltagetransformer
4.DefectiveAss'yPCB
Checkfanmotorwhenthermal
cutoutisdefective.
CheckAss'yPCBwhenL.V.T
isdefective.
Nodisplayandnooperationatall.
Fuseisblown.
1.Shortedleadwireharness
2.Defectiveprimarylatchswitch
(NOTE1)
3.Defectivemonitorswitch(NOTE1)
4.ShortedH.V.Capacitor
5.ShortedH.V.Transformer(NOTE2)
Checkadjustmentofprimary,
interlockmonitor,
powerrelay,doorsensing
switch.
NOTE1:Alloftheseswitchesmustbereplacedatthesametime.
(refertoadjustmentinstructions)
Checkcontinuityofpowerrelaycontactsandifithas
continuity,replacepowerrelayalso.
NOTE2:WhenH.V.Transformerisreplaced,checkdiodeand
magnetronalso.
Ovendoesnotaccept
keyinput(Program)
1.Keyinputisnotin-Sequence
2.Openorlooseconnectionof
membranekeypadtoAss'yPCB
3.Shortedoropenmembranepanel
4.DefectiveAss'yPCB
Refertooperationprocedure.
ReplacePCBmain.
Timerstartscountdownbutno
microwaveoscillation.
(Noheatwhileovenlampandfan
motorturnon.)
1.Off-alignmentoflatchswitches
2.Openorlooseconnectionofhigh
voltagecircuitespecially
magnetronfilamentcircuit
NOTE:Largecontactresistancewill
bringlowermagnetron
filamentvoltageandcause
magnetrontoloweroutput
and/orintermittentoscillation.
3.Defectivehighvoltage
componentsH.V.Transformer
H.V.Capacitor
H.V.Diode,H.V.Fuse
Magnetron
4.Openorloosewiringofpowerrelay
5.Defectiveprimarylatchswitch
6.DefectivepowerrelayorAss'yPCB
Adjustdoorandlatchswitches.
Checkhighvoltagecomponent
accordingto
componenttestprocedureand
replaceifitis
defective.
ReplacePCBmain.
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