Troubleshooting and Testing
3-7
Procedure
Letter
H
I
J
Component Test
BLOWN MONITOR FUSE 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. (See Warnings and Instructions on page 3-1)
4. If the monitor fuse is blown when the door is opened, check the primary interlock relay,
secondary interlock switch and monitor switch according to the “TEST PROCEDURE” for those
switches before replacing the blown monitor fuse.
If the monitor fuse is blown by improper switch operation, the monitor fuse and monitor switch
must be replaced with “monitor fuse and monitor switch assembly”, even if the monitor switch
operates normally. The monitor fuse and monitor switch assembly is comprised of a 20 ampere
fuse and switch.
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.
BLOWN FUSE F10A
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor. (See Warnings and Instructions on page 3-1)
4. Remove the back plate from the oven.
5. If the monitor fuse is blown, there could be short or ground in high voltage rectifier, magnetron,
power transformer, high voltage capacitor or high voltage wire. Check them and replace the de-
fective parts or repair the wire harness. Only replace fuse F10a with correct value replacement.
6. Reconnect all leads removed from components during testing.
7. Reinstall the outer case (cabinet).
8. Reconnect the power supply cord after the outer case is installed.
9. Run the oven and check all functions.
MAGNETRON TEMPERATURE FUSE 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. (See Warnings and Instructions on page 3-1)
4. A continuity check across the thermal cut-out terminals should indicate a closed circuit unless
the temperature of the thermal cut-out reaches approximately 302°F (150°C).
An open thermal cut-out indicates overheating of the magnetron. Check for restricted air flow to
magnetron through the vent holes of oven cavity, especially the cooling duct and cooling fan.
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.
Before replacing a blown monitor fuse, test the primary interlock relay, secondary interlock switch,
door sensing switch and monitor switch for proper operation.
If the thermal cut-out indicates open circuit at room temperature, replace the thermal cut-out.
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