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7. Troubleshooting
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.
7-1 Electrical Malfunction
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 thermal cutout
is defective.
Check
Ass’y PCB when Switching tran-
sformer 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 voltage
circuit especially magnetron filament 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 component
according to component test procedure
and replace if it is
defective.
Replace PCB main.
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