27
THE MICROWAVE SYSTEM
With the Microwave System energized, the volt meter
will read
208-240 VAC. If the meter reads 0 VAC,
the High Voltage Transformers are most likely wired
in-phase. As a last check, energize the Microwave
System and verify the voltages between taps
1&2
and 1&3on each High Voltage Transformer. If the
voltages are not
208 VAC between 1&2and 240
between 1&3, the wiring issue must be corrected
prior to returning the oven to service.
: The terminals with the Orange Dot or
the Orange Wire always go to Terminal
3.
Wiring the Filament T
r
ansformers
The installation of Filament Transformers is
straightfor
ward. Filament Transformers are wired
in-phase and in-line. Refer to Figure 19, detailing
the proper wiring of Filament Transformers.
To verify corr
ect wiring, measur
e the v
oltages
between Terminal
1&2and 1&3on FT1 and FT2.
The voltages must be 208 and 240VAC respectively.
: The Terminals with the Orange Dot or the
Orange Wire always go to Terminal
3.
MEA
SURING RF LEAKAGE FOR MICROWAVE SAFETY
An RF (Microwave) leakage test must be performed
at the conclusion of the following service tasks:
o
Door removal, replacement and/or adjustment
o
Wave Guide removal and/or replacement
o
Magnetron removal and/or replacement
: If the unit fails the radiation
test (leakage greater than 4 mW/cm2), the
oven must be taken out of service immediately until
the defect is corrected. In addition, the CDRH
Regulations 21 Subpart C, 1002.20 requires that
leakage readings of over 4 mW/cm2 must be
reported to the manufacturer.
Procedure for Measuring RF Leakage
1. Place the oven in Warm-up Mode and allow it to
warm-up to the Cook Set Temperature (TSET).
This should take no more than 10 minutes.
2. Once the oven has warmed-up, place the oven
into Test Mode (see page 12). Place a water load
into the Cavity. Water load must conform to the
following specification:
a. Volume: 275ml ± 15ml
b. Temperature: 68 ± 9
º
F
c. Vessel: Low form, 600 ml beaker with an
inside diameter of approximately 3.35” and
made of P
yr
ex or glass ceramic
3. Position the Microwave Survey Meter as shown
in F
igur
e 20.
4.
Press and hold the “MGTRON” Soft Key to
energize the Microwave System.
5. While holding the “MGTRON” Soft Key, move
the S
ur
v
ey M
eter ar
ound the outline of the Cook
Door keeping the tip of the Meter in contact with
and perpendicular to the Cook D
oor
. R
ecor
d the
highest leakage.
6. Using the same procedure, measure the leakage
with the Cook Door opened to the point just
before the Primary/Secondary Switches disengage.
Record the highest leakage.
: Microwave Survey Meter Placement
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