D: High Voltage Capacitor Test; E: Temperature Fuse Or Thermal Cut-Out Test; F: Secondary Interlock Switch Test; F: Primary Interlock System Test - Sharp R-305MR Service Manual

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.

[4] D: HIGH VOLTAGE CAPACITOR 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. If the capacitor is open, no high voltage will be available to the magnetron. Disconnect input leads and check for short or open between the termi-
nals using an ohmmeter.
Checking with a high ohm scale, if the high voltage capacitor is normal, the meter will indicate continuity for a short time and should indicate an
open circuit once the capacitor is charged. If the above is not the case, check the capacitor with an ohmmeter to see if it is shorted between either
of the terminals and case. If it is shorted, replace the capacitor.
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.

[5] E: TEMPERATURE FUSE OR THERMAL CUT-OUT 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. Check a continuity across the temperature fuse or thermal cut-out terminals in the table below.
Temperature of "ON" condition
Parts Name
Temperature fuse 150°C
Thermal cut-out 145°C
5. An open temperature fuse (Magnetron) or thermal cut-out (Magnetron) indicates overheating of the magnetron. Check for restricted air flow to the
magnetron, especially the cooling fan and air guide.
An open temperature fuse (Oven) or thermal cut-out (Oven) indicates overheating of the oven, exchange the temperature fuse or thermal cut-out
and check inside of oven cavity and for improper setting of cooking time or operation of control unit. Check for restricted air flow through the vent
holes of the oven cavity, especially the cooling fan and air guide.
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.
CAUTION: IF THE TEMPERATURE FUSE OR THERMAL CUT-OUT INDICATES AN OPEN CIRCUIT AT ROOM TEMPERATURE, REPLACE IT.

[6] F: SECONDARY INTERLOCK SWITCH 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 switch and connect the ohmmeter to the common (COM.) and normally open (NO) terminal of the switch. The meter should indicate an
open circuit with the door open and a closed circuit with the door closed. If improper operation is indicated, replace the secondary interlock 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.

[7] F: PRIMARY INTERLOCK SYSTEM TEST

1. DOOR SENSING SWITCH
1. Disconnect the power supply cord, and then remove outer case.
Table: Temperature Fuse and Thermal Cut-out Test
(closed circuit).
This is not resetable type.
This is not resetable type.
Temperature of "OFF" condition
(open circuit).
Above 150°C (302°F)
Above 145°C (293°F)
8 – 2
Indication of ohmmeter (When room
temperature is approx. 20°C.)
Closed circuit
Closed circuit
R305MR