Troubleshooting - Samsung CM1629 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 TRANSFORMER, DISCONNECT LEAD
WIRES 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 DIS-
CHARGE MAY DAMAGE 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 opera-
tion.
No display and no
operation Fuse is
blown.(10A, 1.6A)
Oven does not accept
key input (Program)
Timer starts countdown but
no microwave oscillation.
(No heat while oven lamp
and fan motor turn on.)
PRECAUTION
CAUSE
1. Open or loose lead wire harness
2. Open thermal cutout (Magnetron,
cavity)
3. Open low voltage transformer
4. Defective Ass'y PCB
1. Shorted lead wire harness
2. Defective primary latch switch (NOTE 1)
3. Defective monitor switch (NOTE 1)
4. Shorted H.V.Capacitor
5. Shorted H.V.Transformer (NOTE 2)
NOTE 1: All of these switches must be replaced at the same time. (refer to ad-
justment 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.
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. 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.
2. Defective high voltage components
H.V.Transformer H.V. Capacitor
H.V.Diode, H.V.Fuse Magnetron
- 21 -
CORRECTIONS
Check fan motor when thermal
cutout is defective.
Check Ass'y PCB when L.V.T is
defective.
Check adjustment of primary, inter-
lock monitor, door sensing switch.
Refer to operation procedure.
Replace PCB main.
Adjust door and latch switches.
Check high voltage component ac-
cording to component test proce-
dure and replace if it is
defective.