Panasonic NN-L750WB, Service Manual

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8.2 Inverter Warnings
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DANGER, HIGH VOLTAGE AND HIGH TEMPERATURE (HOT/LINE) OF THE
INVERTER POWER SUPPLY (U)
This high voltage inverter power supply handles very high voltage and very high current for the
magnetron tube. Though it is free from danger in ordinary use, extreme care should be taken during
repair. As you can see, it looks like a TV flybacktransformer, however, the current is extremely large
and is therefore, dangerous due to this high current and high voltage.
The aluminium heat sink is also energized with high voltage (HOT), so do not touch when the AC
input terminal is connected. The power devices (Collector) is directly connected to the aluminium
heat sink.
The aluminium heat sink may be (HOT) due to heat energy, therefore, extreme care should be taken
during servicing.
Figure 1
HV Inverter warning
WARNING FOR INVERTER POWER SUPPLY (U) GROUNDING
Check the high voltage inverter power supply circuit grounding. This high voltage inverter power
supply circuit board must have a proper chassis ground, the inverter grounding bracket must be
connected to the chassis. If the inverter board is notgrounded it will expose very high voltages and
cause extreme DANGER! Be sure that the inverter circuit is properly grounded via the inverter earth
bracket.
Figure 2
Grounding of the inverter circuit board
WARNING! DISCHARGE THE HIGH VOLATGE CAPACITORS