Sharp R-501FK Service Manual - Page 14

If The Temperature Fuse Indicates An Open Circuit At Room

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R-501FK R-501FW TEST PROCEDURES PROCEDURE LETTER C COMPONENT TEST 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. 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 terminals 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. E CAVITY 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. 4. A continuity check across the cavity temperature fuse terminals should indicate a closed circuit unless the temperature of the cavity temperature fuse reaches approximately 302OF(150OC). An open cavity temperature fuse indicates overheating of the oven, exchange the cavity temperature fuse 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. 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. C/T 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. 4. A continuity check across the C/T fuse terminals should indicate a closed circuit unless the temperature of the C/T fuse reaches approximately 302OF(150OC). An open C/T fuse indicates overheating of the magnetron. Check for restricted air flow to the magnetron, especially the cooling fan air guide. CAUTION: IF THE TEMPERATURE FUSE INDICATES AN OPEN CIRCUIT AT ROOM TEMPERATURE, REPLACE TEMPERATURE FUSE. 12

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12
R-501FK
R-501FW
TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT 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 terminals 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.
D
HIGH VOLTAGE CAPACITOR TEST
E
CAVITY 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.
4.
A continuity check across the cavity temperature fuse terminals should indicate a closed circuit unless
the temperature of the
cavity temperature fuse reaches approximately 302
O
F(150
O
C).
An open
cavity
temperature fuse indicates overheating of the oven, exchange the
cavity temperature fuse 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.
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.
C/T 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.
4.
A continuity check across the C/T fuse terminals should indicate a closed circuit unless the temperature
of the C/T fuse reaches approximately 302
O
F(150
O
C). An open C/T fuse indicates overheating of the
magnetron. Check for restricted air flow to the magnetron, especially the cooling fan air guide.
CAUTION:
IF THE TEMPERATURE FUSE INDICATES AN OPEN CIRCUIT AT ROOM
TEMPERATURE, REPLACE TEMPERATURE FUSE.
C
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.