Sharp SMD2470AHA Service Manual page 21

UPDATE
PROCEDURE
LETTER
N NOISE FILTER TEST
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4. Disconnect the leads to the primary of the power transformer.
5. Using an ohm-meter, check between the terminals as described in the following table:
MEASURING POINT
Between N and H
Between terminal N and LOAD
Between terminal H and LOAD
Fuse
If fuse is open, replace fuse
If incorrect readings are obtained, replace the noise filter.
6. Reconnect all leads removed from components during testing.
7. Re-install the outer case (cabinet).
8. Reconnect the power supply cord after the outer case is installed.
9. Run the oven and check all functions.
O HIGH VOLTAGE RECTIFIER TEST
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4. Isolate the rectifier from the circuit. Using the highest ohm scale of the meter, read the resistance
across the terminals and observe, reverse the leads to the rectifier terminals and observe meter
reading. If a short is indicated in both directions, or if an infinite resistance is read in both directions,
the rectifier is probably defective and should be replaced.
5. Reconnect all leads removed from components during testing.
6. Reinstall the outer case (cabinet).
7. Reconnect the power supply cord after the outer case is installed.
8. Run the oven and check all functions.
NOTE: Be sure to use an ohmmeter that will supply a forward bias voltage of more than 6.3 volts.
TEST PROCEDURES
N NOISE FILTER UNIT
"TO SOURCE"
RESISTOR 470 K Ω 1/2W
LINE CROSS CAPACITOR 1.0 µF 275V
NOISE SUPPRESSION COIL
LINE BYPASS CAPACITOR
0.0022 µF/ 250v
TO LOAD
COMPONENT TEST
"TO SOURCE" H
MONITOR
FUSE
LINE BYPASS CAPACITOR
0.0022 µF/ 250v
TO LOAD
INDICATION OF OHM-METER
275 - 415Ω
Short Circuit
Short Circuit
Short Circuit
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SMD2470AHA