Troubleshooting; Electrical Malfunction - Samsung ME21F707MJT Service Manual

5. 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.

5-1 Electrical Malfunction

Oven is dead. (No display and no operation at all.)
Fuse is OK
Oven does not accept key input (Program)
Oven does not
accept key input
Open or loose lead wire harness
Open thermal cutout (Magnetron)
Open low voltage transformer
Defective Ass'y PCB
Shorted lead wire harness
Defective primary latch switch
(NOTE 1)
Defective monitor switch
(NOTE 1)
Shorted H.V.Capacitor
Shorted H.V.Transformer
(NOTE 2)
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 H.V.Transformer is replaced, check diode and magnetron also.
Key input is not in-Sequence
Open or loose connection of
membrane key pad to Ass'y PCB
Shorted or open membrane panel
Defective Ass'y PCB
30
Check fan motor when thermal cutout is defective.
Check Ass'y PCB when L.V.T is defective.
Check adjustment of primary, interlock monitor,
power relay, door sensing switch.
Refer to operation procedure.
Replace PCB main.