Magnetrons; Testing A Magnetron For An Open/Shorted Filament; Stirrer Motor And Assembly; Waveguides - TurboChef ngo Service Manual

26 OVEN SYSTEMS

Magnetrons

Figure 32. 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.
Perform a microwave leakage test (page 22) after
installing a new magnetron or reinstalling an old
one.
CAUTION: Do not allow debris to enter
the waveguides when servicing the
magnetrons.
FA
Figure 32: 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 32.
F
FILAMENT AND
Filament and High
HIGH VOLTAGE
Voltage Terminals
TERMINALS
ANTENNA
Antenna
3. An ohmmeter connected between the filament
terminals (F, FA) should indicate a reading of less
than 1 ohm. Figure 32.
4. A continuity check between either filament
terminal and the magnetron chassis should
indicate an infinite resistance (open).
CAUTION: Do not allow debris to enter
the waveguides when servicing the
magnetrons.

Stirrer Motor and Assembly

The stirrer is responsible for evenly distributing hot
air and microwave that enters the cook cavity from
the top. 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 14).
CAUTION: Do not allow debris to enter the
waveguides when servicing the stirrer.

Waveguides

The waveguides channel microwave into the cook
cavity. If debris or contamination gets into the
waveguides, the life of the magnetrons may be
shortened. Be careful to not allow debris into the
waveguides when servicing the magnetrons or stirrer
assembly.
NOTE: The Single Mgnetron Sota uses only one
waveguide.

Troubleshooting

The following faults may occur in relation to the
microwave system:
- F3: Magnetron Current Low (see page 35)
- F5: Magnetron Over Temperature (see page 36)
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 (see page 41)