Panasonic NN-F623MF, Service Manual

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microwave power since approximately 2 seconds are required for
heating of magnetron filament.
Variable Power Cooking
POWER SETTING OUTPUT
POWER(%)
APPROX.
ON-OFF TIME OF
POWER RELAY
(RY1)
ON(SEC) OFF(SEC)
HIGH
P10
100% 22 0
P9 90% 22 0
P8 80% 22 0
MEDIUM-HIGH P7 70% 22 0
MEDIUM P6 60% 22 0
P5 50% 22 0
P4 40% 22 0
MEDIUM-LOW P3 30% 22 0
P2 20% 15 7
P1 10% 8 14
DEFROST P3 30% 22 0
3.2. Inverter power supply circuit [NEW H.V.]
This Inverter Power Supply Circuit supplies 4,000V DC to the magnetron tube from the line
voltage, 230-240V 50Hz AC input. functions as the H.V. transformer, the H.V.capacitor and
H.V.Diode.
1. The AC input voltage 230-240V 50Hz is rectified to DC voltage
immediately.
2. DC voltage will be supplied to the switching devices called IGBT.
These devices will be switched ON-OFF by the 20 to 40 kHz PWM.
(pulse width modulation) signal from the microcomputer in the
DPC.
3. This drives the High voltage transformer to increase up to 2,000V
AC and approximately 3V AC by means of transformer.
4. Then the half-wave doubler voltage rectifier circuit, consisting of
the H.V. diodes and Capacitors, generates the necessary 4,000V
DC needed for the magnetron.
5. Output power of the magnetron tube is always monitored by the
signal output from the current transformer built into the inverter
circuit.
6. Then this signal will be fed back to the microcomputer in the DPC
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