Cautions To Be Observed When Troubleshooting - Panasonic NN-E251W Service Manual

5. CAUTIONS TO BE OBSERVED WHEN TROUBLESHOOTING

Unlike many other appliances, the microwave oven is high-
voltage, high-current equipment. Though it is free from dan-
ger in ordinary use, extreme care should be taken during
repair.
Servicemen should remove their watches whenever
working close to or replacing the magnetron.
5.1 Check the earthing
Do not operate on a 2-wire extension cord. The microwave
oven is designed to be used in a completely earthed condi-
tion. It is imperative, therefore, to make sure it is properly
earthed before beginning repair work.
5.2 If the door lock, the door switch, the door
seal or the door develops a malfunction, be
sure not to operate the oven until complete
repairs are made
If the oven is operated with any of these parts in imperfect
condition, hazardous microwave leakage may occur.
WARNING
Never operate the oven until the following are confirmed:
• The door is tightly closed.
• There is no broken hinge or door arm.
• The door seal is not damaged.
• The door is not bent or warped.
• There is no other visible damage.
5.3 Warning about the electric charge in the
high voltage capacitor
For about 30 seconds after the oven is turned off, an elec-
tric charge remains in the high voltage capacitor. When
replacing or checking parts, remove the power plug from
the wall outlet, wait 30 seconds and short the terminal of the
high voltage capacitor (Terminal of lead wire from diode) to
chassis ground with an insulated jumper lead wire or an
insulated handle screw driver to discharge.
Touch chassis side first then short to the high voltage
capacitor terminal
CAUTION
IMPORTANT NOTE
High voltage above 250 volts exists on the following parts
during operation.
• Magnetron
• High Voltage Transformer
• High Voltage Diode
• High Voltage capacitor
Pay special attention during repair or troubleshooting in
these areas.
If the microwave oven is operated with incorrectly installed
door hinge or magnetron, it can cause microwave leakage
of over 5mW/cm 2 . Hence it is absolutely necessary to
check if magnetron and door hinge are correctly and safe-
ly installed after repairs or replacement.
Never touch any circuit wiring with your hand nor with an
insulated tool during operation.
5.4 When parts must be replaced, remove the
power plug from the outlet and discharge
the high voltage capacitor
5.5 Confirm after repair
1. After repair or replacement of parts, make sure that the
screws of the oven, etc. are neither loose nor missing.
Microwaves might leak if screws are not properly tightened.
2. Make sure that all electrical connections are tight before
inserting the plug into the wall outlet.
5.6 Avoid inserting nails, wire, etc. through any
holes in the unit 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,
because such objects may work as an antenna and cause
microwave leakage.
5.7
MICROWAVE RADIATION
Personnel should not be exposed to the microwave energy
which may radiate from the magnetron or other microwave
generating device if it is improperly used or connected. All
input and output microwave connections waveguides,
flanges and gasket must be secure. Never operate the
device without a microwave energy absorbing load
attached. Never look into an open waveguide or antenna
while the device is energized.
5.8
High voltage parts may become uncovered when outer
cabinet is removed.
7
WARNING
CAUTION
CAUTION