Sharp SMD2499FS Service Manual page 21

PROCEDURE
LETTER
N MOTOR WINDING TEST
Disconnect the leads from the motor. Using an ohmmeter, check the resistance between the two
terminals as described in the table below.
LIVE TEST FOR MOTOR WINDING
CAUTION: The following procedure requires the oven to be connected to the supply and should only be
(without damper motor )
1. Unplug
2. Disconnect the leads from the primary of the high voltage transformer. Make sure that the leads remain
isolated from other oven components and chassis (Use insulation tape if necessary.)
3. Connect the voltmeter, set to 220V AC, across the motor terminals. (Refer to the relevant motor test
procedure or pictorial diagram for the correct terminal numbers.)
4. Arrange the meter in a position where it can be read during the test.
(Do not touch the meter, meter leads or oven circuitry while the oven is active.)
5. Close the oven door.
6. Plug
7. Set the power level to 0% and set the relevant timer for about three (3) minutes.
8. Note the reading on the meter and carefully observe the motor under test to see if it is turning.
9. Remove the test meter leads.
10. Reconnect the leads to the primary of the high voltage transformer.
(damper motor )
1. Unplug
2. Disconnect the leads from the primary of the high voltage transformer. Make sure that the leads remain
isolated from other oven components and chassis (Use insulation tape if necessary.)
3. Connect the voltmeter, set to 220V AC, across the motor terminals. (Refer to the relevant motor test
procedure or pictorial diagram for the correct terminal numbers.)
4. Arrange the meter in a position where it can be read during the test.
(Do not touch the meter, meter leads or oven circuitry while the oven is active.)
5. Close the oven door.
6. Plug
7. Note the reading on the meter and carefully observe the motor under test to see if it is turning.
8. Remove the test meter leads.
9. Reconnect the leads to the primary of the high voltage transformer.
If a reading of the line voltage was obtained (step 7) but the motor was not turning then it is faulty and should
be replaced. If the meter indicated that the no supply was present then the winding to the motor should be
checked for continuity or other circuit checks should be made, i.e. relays, switches.
TEST PROCEDURES
Table: Resistance of Motor
Motors
Antenna motor
Fan motor
MG fan motor
Rear Convection motor
Top conv motor (DC)
Intake damper motor
Exhaust damper motor
used if the relevant "cold" checks for the motor under test are inconclusive.
COMPONENT TEST
Resistance
Approximately 3.6 – 4.0 kΩ
Approximately 12 - 16 Ω
Approximately 15 - 19 Ω
Approximately 45 - 55 Ω
Cannot check
Approximately 3.6 – 4.0 kΩ
Approximately 3.6 – 4.0 kΩ
21
SMD2499FS