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1. Precaution
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1. Precaution
Follow these special safety precautions. Although the microwave oven is completely safe during ordinary use,
repair work can be extremely hazardous due to possible exposure to microwave radiation, as well as potentially
lethal high voltages and currents.
1-1 Safety precautions ( )
1. All repairs should be done in accordance with the
procedures described in this manual. This product
complies with Federal Performance Standard 21
CFR
2. Microwave emission check should be performed to
prior to servicing if the oven is operative.
3. If the oven operates with the door open :Instruct
the user not to operate the oven and contact
the manufacturer and the center for devices and
radiological health immediately.
4. Notify the Central Service Center if the microwave
leakage exceeds 5 mW/cm2.
5. Check all grounds.
6. Do not power the MWO from a “2-prong” AC cord.
Be sure that all of the built-in protective devices are
replaced. Restore any missing protective shields.
7. When reinstalling the chassis and its assemblies,
be sure to restore all protective devices, including:
nonmetallic control knobs and compartment covers.
8. Make sure that there are no cabinet openings
through which people --particularly children--might
insert objects and contact dangerous voltages.
Examples: Lamp hole,ventilation slots.
9. Inform the manufacturer of any oven foundto have
emission in excess of 5 mW/cm2 ,Make repairs to
bring the unit into compliance at no cost to owner
and try to determine cause. Instruct owner not to use
oven until it has been brought into compliance.
CENTRAL SERVICE CENTER
10. Service technicians should remove their watches
while repairing an MWO.
11. To avoid any possible radiation hazard,replace parts
in accordance with the wiring diagram. Also, use
only the exact replacements for the following parts:
Primary and secondary interlock switches, interlock
monitor switch.
12. If the fuse is blown by the Interlock Monitor Switch:
Replace all of the following at the same time:
Primary, door sensing switch and power relay, as
well as the Interlock Monitor Switch. The correct
adjustment of these switches is described elsewhere
in this manual. Make sure that the fuse has the
correct rating for the particular model being repaired.
13. Design Alteration Warning: Use exact replacement
parts only, i.e.,only those that are specied in
thedrawings and parts lists of this manual. This
is especially important for the Interlock switches,
described above. Never alter or add to the
mechanical or electrical design of the MWO.
Any design changes or additions will void the
manufacturer’s warranty. Always unplug the unit’s
AC power cord from the AC power source before
attempting to remove or reinstall any component or
assembly.
14. Never defeat any of the B+ voltage interlocks. Do not
apply AC power to the unit (or any of its assemblies)
unless all solid-state heat sinks are correctly
installed.
15. Some semiconductor (“solid state”) devices
are easily damaged by static electricity. Such
components are called Electrostatically Sensitive
Devices (ESDs). Examples include integrated
circuits and eld-effect transistors. Immediately
before handling any semiconductor components or
assemblies, drain the electrostatic charge from your
body by touching a known earth ground.
16. Always connect a test instrument’s ground lead to
the instrument chassis ground before connecting the
positive lead; always remove the instrument’s ground
lead last.
17. When checking the continuity of the witches or
transformer, always make sure that the power is
OFF, and one of the lead wires is disconnected.
18. Components that are critical for safety are indicated
in the circuit diagram by shading, or .
19. Use replacement components that have the same
ratings, especially for ame resistance and dielectric
strength specications. A replacement part that does
not have the same safety characteristics as the
original might create shock, re or other hazards.
NOTE : Connect the oven to a 20A. When
connecting the oven to a 15A,make sure that circuit
breaker can operate.
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1. Precaution
1-2 Special High Voltage Precautions
1. High Voltage Warning Do not attempt to measure any of
the high voltages --this includes the lament voltage of the
magnetron. High voltage is present during any cook cycle.
Before touching any components or wiring, always unplug
the oven and discharge the high voltage capacitor (See
Figure 1-1)
2. The high-voltage capacitor remains charged about 30
seconds after disconnection. Short the negative terminal
of the high-voltage capacitor to to the oven chassis. (Use a
screwdriver.)
3. High voltage is maintained within specied limits by closetolerance, safety-related components and adjustments. If
the high voltage exceeds the specied limits, check each
of the special components.
PRECAUTION
There exists HIGH VOLTAGE ELECTRICITY with high current capabilities in the circuits of the HIGH
VOLTAGE TRANSFORMER secondary and lament terminals. It is extremely dangerous to work on or
near these circuits with the oven energized.
DO NOT measure the voltage in the high voltage circuit including lament voltage of magnetron.
PRECAUTION
Servicemen should remove their watches whenever working close to or replacing the magnetron.
PRECAUTION
Never touch any circuit wiring with your hand nor with uninsulated tool during operation.
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