Samsung CM1929 - Troubleshooting; Electrical Malfunction

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6. 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.
6-1 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. Defective Ass’y PCB
Check fan motor when thermal cutout
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 H.V.Capacitor
5. Shorted H.V.Transformer (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 H.V.Transformer 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. Open or loose connection of high
voltage circuit especially magnetron
lament circuit
NOTE : Large contact resistance will
bring lower magnetron lament
voltage and cause magnetron to
lower output and/or intermittent
oscillation.
2. Defective high voltage components
H.V.Transformer H.V. Capacitor
H.V.Diode, H.V.Fuse Magnetron
Adjust door and latch switches.
Check high voltage component
according to component test
procedure and replace if it is
defective.