8
R-120DB
R-120DK
R-120DR
R-120DW
air is channelled through the oven cavity to remove steam
and vapours given off from the heating foods. It is then
exhausted through the exhausting air vents at the oven
cavity.
MAGNETRON THERMAL CUT-OUT
The thermal cut-out located on the air duct is designed to
prevent damage to the magnetron if an over heated condi-
tion develops in the tube due to cooling fan failure, ob-
structed air guide, dirty or blocked air intake, etc.
Under normal operation, the thermal cut-out remains closed.
However, when abnormally high temperatures are reached
within the magnetron, the thermal cut-out will open at 203˚F
(95˚C), causing the oven to shut down. The thermal cut-out
will reset automatically below approximately 167˚F(75˚C).
TROUBLESHOOTING GUIDE
Never touch any part in the circuit with your hand or an uninsulated tool while the power supply is connected.
When troubleshooting the microwave oven, it is helpful to follow the Sequence of Operation in performing the checks. Many
of the possible causes of trouble will require that a specific test be performed. These tests are given a procedure letter which
will be found in the "Test Procedure "section.
IMPORTANT: If the oven becomes inoperative because of a blown C/T fuse, check the monitor switch, primary
interlock relay (RY2), door sensing switch and secondary interlock switch before replacing the C/T fuse.
If the C/T fuse is replaced, the monitor switch must also be replaced. Use part FFS-BA027WRKZ as an
assembly.
IMPORTANT: Whenever troubleshooting is performed with the power supply cord disconnected. It may, in some cases,
be necessary to connect the power supply cord after the outer case has been removed, in this event,
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. Ensure that the leads remain isolated from other components and oven chassis by using insulation tape.
6. After that procedure, reconnect the power supply cord.
When the testing is completed,
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. Reconnect all leads removed from components during testing.
5. Reinstall the outer case (cabinet).
6. Reconnect the power supply cord after the outer case is installed.
7. Run the oven and check all functions.
C/T FUSE
1. The C/T fuse blows when the contacts (COM-NO) of the
primary interlock relay (RY2) and secondary interlock
switch remain closed with the oven door open and when
the monitor switch closes.
2. If the wire harness or electrical components are short-
circuited, this C/T fuse blows to prevent an electric shock
or fire hazard.
3. The C/T fuse, located on the top of the oven cavity, is
designed to prevent damage to the oven by fire. If the
food load is overcooked, by either error in cook time or
defect in the timer, the C/T fuse will open.
Under normal operation, the C/T fuse remains closed.
However, when abnormally high temperatures are reached
within the oven cavity, the C/T fuse will open at 248˚F
(120˚C), causing the oven to shut down or when the electric
currents beyond 13A flow, the C/T fuse will open.
