Sharp R-55TS-F Service Manual page 18

R-55TS-F
PROCEDURE
LETTER
are operating properly, according to the above Switch Test Procedure. Disconnect the wire lead from the
monitor switch (COM) terminal. Check the monitor switch operation by using the ohmmeter as follows.
When the door is open, the meter should indicate a closed circuit. When the monitor switch actuator is
pushed by a screw driver through the lower latch hole on the front plate of the oven cavity with the door
opened (in this condition the plunger of the monitor switch is pushed in), the meter should indicate an open
circuit. If improper operation is indicated, the switch may be defective. After testing the monitor switch,
reconnect the wire lead to the monitor
switch (COM) terminal and check the
continuity of the monitor circuit.
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.
H 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.
4. If the monitor fuse is blown when the door is opened, check the primary interlock relay (RY2), relay (RY1),
secondary interlock switch and monitor switch according to the "TEST PROCEDURE" for those switches
before replacing the blown Monitor fuse.
CAUTION: BEFORE REPLACING A BLOWN MONITOR FUSE, TEST THE PRIMARY INTERLOCK
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" part number FFS-BA038WRKZ, even if the monitor
switch operates normally. The monitor fuse and monitor switch assembly is comprised of a 15 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.
I UPPER HEATER AND LOWER HEATER 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. Make sure the heater is cooled completely.
5. Resistance of heater.
Disconnect the wire leads to the heater to be tested. Using ohmmeter with low resistance range. Check
the resistance across the terminals of the heater as described in the following table.
6. Insulation resistance.
Disconnect the wire leads to the heater to be tested. Check the insulation resistance between the heater
terminal and cavity using a 500V - 100MΩ insulation tester. The insulation resistance should be more
than 10 MΩ in the cold start.
7. If the results of above test 5 and/or 6 are out of above specifications, the heater is probably faulty and
should be replaced.
8. Reconnect all leads removed from components during testing.
TEST PROCEDURES
RELAY (RY2), RELAY (RY1), SECONDARY INTERLOCK SWITCH, DOOR SENSING
SWITCH AND MONITOR SWITCH FOR PROPER OPERATION.
Table: Resistance of heater
Parts name
Upper heater
Lower heater
COMPONENT TEST
RED
Screw Driver
Resistance
Approximately 18.9 Ω
Approximately 28.2 Ω
16
BLU/WHT
Monitor
Switch
Ohmmeter
Secondary
Interlock Switch