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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
Subchapter J(DHHS).
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 found to 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.
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 specified in the drawings 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 field -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 flame resistance and dielectric
strength specifications. A replacement part that does
not have the same safety characteristics as the
original might create shock, fire or other hazards.
