Testing A High-Voltage Diode; Magnetrons; Magnetron Cooling Fans - TurboChef encore Service Manual

High voltage Transformers
NGC-3062-1
NGC-3062-2
filament Transformers
NGC-3061-1
NGC-3061-2

Testing a High-voltage diode

DANGEr: Never attempt to measure high
voltage directly. Death or serious injury
could result.
1. Disconnect the oven from the power source.
2. Fully discharge the capacitors.
3. Connect the voltage meter in series with high-
voltage diode.
4. using a multimeter set to DC voltage, connect
one meter lead to one side of a 9-volt battery and
the other lead to one side of the high-voltage diode.
5. Connect the other side of the 9-volt battery to the
other side of the high-voltage diode. DC voltage
should be present on the meter in only one direction.
6. Switch the meter leads on the high-voltage diode,
which will cause the opposite reading to be
visible. Depending on the voltage of the battery,
voltage between 5-7 VDC should be present in
only one direction and 0-0.1 VDC in the other
direction.
Primary voltage, frequency, Taps,
and Resistance
208 VAC, 60 Hz, 1 & 2,
0.819–1.001 Ω
240 VAC, 60 Hz, 1 & 3,
0.972–1.188 Ω
230 VAC, 50 Hz, 1 & 2,
0.972–1.188 Ω
Primary voltage, frequency, Taps,
and Resistance
208 VAC, 60 Hz, 1 & 2,
17.49–21.37 Ω
240 VAC, 60 Hz, 1 & 3,
20.61–25.19 Ω
230 VAC, 50 Hz, 1 & 2,
18.99–23.21 Ω

Magnetrons

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 26) after
installing a new magnetron or reinstalling an old one.
CAuTIoN: Do not allow debris to enter
the waveguides when servicing the magnetrons.

Magnetron Cooling fans

The magnetron cooling fans (outer fans on the
back panel) are actuated by the K7 relay when the
magnetrons are in operation, and remain on for four
minutes and fifteen seconds after the magnetrons turn
off. They operate at:
- 208/240 VAC (60 Hz with voltage sensing)
- 220 VAC (60 Hz with no voltage sensing)
- 230 VAC (50 Hz installations)
NoTE: In the Encore 2, the magnetron cooling fans
are actuated by the K7 relay when the EC temperature
exceeds 120°F (49°C), regardless of magnetron
operation.
Secondary Taps and Resistance
4, Ground, 53.60–65.52 Ω
3, Ground, 57.52–70.30 Ω
Secondary Taps and Resistance
4, 5, very low resistance - if reading
is open, transformer has failed.
4, 5, very low resistance - if reading
is open, transformer has failed.
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