Troubleshooting; Electrical Malfunction - Samsung CK135 Service Manual

6. Troubleshooting

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 TRANSFORM ER, DISCONNECT ONE LEAD WIRE FROM THESE
PARTS AND THEN CHECK CONTINUITY WITHOUT THE POWER SOURCE ON. TO DO OTHERWISE M AY RESULT IN A FALSE
READING OR DAM AGE TO YOUR M ETER.
5. DO NOT TOUCH ANY PART OF THE CIRCUIT OR THE CONTROL CIRCUIT BOARD, SINCE STATIC DISCHARGE M AY DAM AGE IT.
ALWAYS TOUCH GROUND WHILE WORKING ON IT TO DISCHARGE ANY STATIC CHARGE BUILT UP.

6-1 Electrical Malfunction

SYMPTOM
Oven is dead.
Fuse is OK.
No display and no operation at all.
No display and no operation at all.
Fuse is blow n.
Oven does not accept
key input (Program)
Timer starts countdow n but no
microw ave oscillation.
(No heat w hile oven lamp and
fan motor turn on.)
Samsung Electronics
PRECAUTION
CAUSE
1. Open or loose lead w ire harness
2. Open thermal cutout (M agnetron)
3. Open low voltage transformer
4. Defective Ass'y PCB
1. Shorted lead w ire harness
2. Defective primary latch sw itch (NOTE 1)
3. Defective monitor sw itch (NOTE1)
4. Shorted HVCapacitor
5. Shorted HVTransformer (NOTE2)
NOTE 1: All of these sw itches must be replaced at the same time.
(refer to adjustment instructions)
Check continuity of pow er relay contacts and if it has continuity, replace pow er
relay also.
NOTE 2: When HVTransformer is replaced, check diode and magnetron also.
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
1. Off-alignment of latch sw itches
2. Open or loose connection of high voltage
circuit especially magnetron filament
circuit
NOTE: Large contact resistance w ill bring
low er magnetron filament voltage and
cause magnetron to low er output and/ or
intermittent oscillation.
3. Defective high voltage components
H.V.Transformer
H.V.Capacitor
H.V.Diode,H.V.Fuse
M agnetron
4. Open or loose w iring of pow er relay
5. Defective primary latch sw itch
6. Defective pow er relay or Ass'y PCB
CORRECTIONS
Check fan motor when thermal cutout is defective.
Check Ass'y PCB w hen LVT is defective.
Check adjustment of primary, interlock monitor,
pow er relay, door sensing sw itch.
Refer to operation procedure.
Replace PCB main.
Adjust door and latch sw itches.
Check high voltage component according to
component test procedure and replace if it is
defective.
Replace PCB main.
6-1