Precautions To Be Observed While Troubleshooting - Whirlpool SPEEDCOOK GH6208 XR Technical Education

PRECAUTIONS TO BE OBSERVED WHILE TROUBLESHOOTING

The microwave oven is a high voltage, high
current appliance. It is free from danger dur-
ing ordinary use, but extreme care should be
taken during repair.
CAUTION
Service technicians should remove their
watches whenever working close to or re-
placing the magnetron.
DANGER
HIGH VOLTAGE AND HIGH TEMPERA-
TURE (HOT/LIVE) OF THE INVERTER
POWER SUPPLY
The high voltage inverter power supply cir-
cuit supplies 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. The
current is extremely large, and so danger
exists because of its high current and high
voltages.
The aluminum heat sink is also energized
with high voltage (HOT), so do not touch it
when the AC input terminal is connected to
the power line. One of the IGBT switching
power devices (collector) is directly con-
nected to the aluminum heat sink.
The aluminum heat sink may be HOT from
heat energy; therefore, extreme care should
be taken during servicing and replacing.
WARNING
INVERTER POWER
SUPPLY GROUNDING
Check the high voltage inverter power supply
circuit grounding. This high voltage inverter
power supply circuit board must have a proper
chassis ground by the grounding bracket
to the chassis ground; otherwise, this H.V.
inverter circuit board will expose very high
voltage, and cause extreme DANGER. Be
sure to have proper grounding by the ground-
ing plate and screws.
DISCHARGING HIGH
VOLTAGE CAPACITORS
For about 30 seconds after the oven is
turned off, an electric charge remains in the
high voltage capacitors in the inverter power
supply circuit board.
When replacing or checking parts, remove
the power plug from the outlet. Use a screw-
driver with an insulated handle, and short
the inverter output of the magnetron filament
terminals to discharge it. Be sure to touch
the chassis ground side first, and then touch
the output terminals.
There is high voltage present, with high cur-
rent capabilities in the circuits of the primary
and secondary windings, the choke coil, and
the heat sink of the inverter. It is extremely
dangerous to work on or near these circuits
with the microwave oven energized. DO
NOT measure the voltage in the high volt-
age circuit, including the filament voltage of
the magnetron.
Never touch any circuit wiring with your hand,
or with an insulated tool during operation.
Never insert a wire, nail, or any other metal
object through the lamp holes on the cavity,
or any other holes or gaps. Doing so may
act as an antenna, and cause microwave
leakage.
Before touching any oven components or
wiring, always unplug the oven from its power
source, and discharge the capacitors in the
high voltage inverter.
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WARNING
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