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32 OVEN SYSTEMS
Magnetrons
Figure 30. Magnetrons supply the RF energy at
2.45 GHz and begin to oscillate when they are
supplied with approximately 4.1 kVDC at
approximately .350 mA. During operation each
magnetron will output a nominal 1 kW of power.
If replacement is required, conduct a microwave
leakage test (page 27) after installation of new
magnetron.
Testing a Magnetron for an Open/Shorted
Filament
DANGER: The only safe way to test a
magnetron is by a resistance test of its
filament. Never attempt to measure the magnetron
using any other method while the microwave
system is on. Death or serious injury could occur.
1. Disconnect the AC power source and discharge
the high-voltage capacitors.
2. Isolate the magnetron from the circuit by
removing the wires from the F and FA terminals.
Figure 30.
3. An ohmmeter connected between the filament
terminals (F, FA) should indicate a reading of less
than 1 ohm. Figure 30.
4. A continuity check between either filament
terminal and the magnetron chassis should
indicate an infinite resistance (open).
CAUTION: Be careful to not allow debris
into the wave guides when servicing the
magnetrons.
Stirrer Motor and Assembly
The stirrer is responsible for evenly distributing hot
air and microwaves that are launched from the top
of the oven into the cook cavity. The stirrer is
driven by a 3.6 RPM motor, which remains on
during a cook cycle or when the oven is in
TEST
MODE
.
The stirrer motor can be tested in
TEST MODE
(see
page 15).
CAUTION: Be careful to not allow debris
into the waveguides when servicing the
stirrer assembly.
Wave Guides
The wave guides channel microwave into the cook
cavity. If debris or contamination gets into the wave
guides, the life of the magnetrons may be
shortened. Be careful to not allow debris into the
waveguides when servicing the magnetrons or
stirrer assembly.
Troubleshooting
The following faults may occur in relation to the
microwave system:
- F3: Magnetron Current Low (see page 41)
- F5: Magnetron Over Temperature (see page 42)
The following issues may occur in relation to the
microwave system:
- Electrical component failure (blank or
scrambled display, damaged control board, etc.)
- Food not cooking properly
ANTENNA
FFA
FILAMENT AND
HIGH VOLTAGE
TERMINALS
Figure 30: Magnetron