Panasonic NN-A890WB, Service Manual

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1. Inverter Warning
The inverter board looks like a regular PCB, however, this PCB drives the magnetron tube using
very high voltages and current.
It has
1. Very high voltage and high current
2. An Aluminium heat sink that becomes very hot
3. The capacitors on the inverter circuit will contain a high voltage
charge even when the oven is not operating.
Do not
1. Do not touch the circuitry as it contains very high voltages. When
replacing the board please take extreme care to avoid possible
electric shock. High voltages may remain in the circuit.
2. Do not touch the aluminium heat sink as it will become very hot. It
also contains high voltages.
3. Do not attempt to repair the inverter PCB as this can be very
dangerous. Replace the high voltage inverter circuit as a complete
unit. Return the old unit fully repacked in the original shipping
box and completed paper work.
4. Do not adjust or tamper with the preset volume on the inverter
board. It is very dangerous to adjust this preset without proper
test equipment.
5. Do not test the oven while the inverter grounding strip or screws
are loose. It is very dangerous to operate the inverter circuit board
without a proper ground connection.
Figure 1
4