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6. Troubleshooting
SYMPTOM
CAUSE
CORRECTIONS
Oven is dead. Fuse is OK.
No display and no operation at all .
1. Open or loose lead wire harness
2. Open thermal cutout (Magnetron)
3. Open low voltage transformer
4. Defective Ass’y PCB
Check fan motor when ther-
mal cutout is defective.
Check Ass’y PCB when LVT is
defective.
No display and no operation at
all. Fuse is blown.
1. Shorted lead wire harness
2. Defective primary latch switch
(NOTE 1)
3. Defective monitor switch
(NOTE1)
4. Shorted HVCapacitor
5. Shorted HVTransformer
(NOTE2)
Check adjustment of primary,
interlock monitor, power relay,
door sensing switch.
NOTE 1
: All of these switches must be replaced at the same time.
(refer to adjustment instructions)
Check continuity of power relay contacts and if it has continuity,
replace power relay also.
NOTE 2
: When HVTransformer is replaced, check diode and magnetron
also.
Oven does not accept
key input (Program)
1. Key input is not in-Sequence
2. Open or loose connection of membrane
key pad to Ass’y PCB
3. Shorted or open membrane panel
4. Defective Ass’y PCB
Refer to operation procedure.
Replace PCB main.
Timer starts countdown but no
microwave oscillation.
(No heat while oven lamp and
fan motor turn on.)
1. Off-alignment of latch switches
2. Open or loose connection of high volt-
age circuit especially magnetron fila-
ment circuit
NOTE
: Large contact resistance will
bring lower magnetron filament
voltage and cause magnetron to
lower output and/or intermittent
oscillation.
3. Defective high voltage components
H.V.Transformer H.V. Capacitor
H.V.Diode, H.V.Fuse Magnetron
4. Open or loose wiring of power relay
5. Defective primary latch switch
6. Defective power relay or Ass’y PCB
Adjust door and latch switches.
Check high voltage compo-
nent according to component
test procedure and replace if
it is
defective.
Replace PCB main.
PRECAUTION
1. CHECK GROUNDING BEFORE CHECKING FOR TROUBLE.
2. BE CAREFUL OF THE HIGH VOLTAGE CIRCUIT.
3. DISCHARGE THE HIGH VOLTAGE CAPACITOR.
4. WHEN CHECKING THE CONTINUITY OF THE SWITCHES OR TRANSFORMER, DISCONNECT ONE LEAD
WIRE FROM THESE PARTS AND THEN CHECK CONTINUITY WITHOUT THE POWER SOURCE ON. TO
DO OTHERWISE MAY RESULT IN A FALSE READING OR DAMAGE TO YOUR METER.
5. DO NOT TOUCH ANY PART OF THE CIRCUIT OR THE CONTROL CIRCUIT BOARD, SINCE STATIC
DISCHARGE MAY DAMAGE IT. ALWAYS TOUCH GROUND WHILE WORKING ON IT TO DISCHARGE
ANY STATIC CHARGE BUILT UP.
6-1 Electrical Malfunction
