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42
OVEn SySTEMS
Power Components
This section contains information about the
following components:
- Electrical compartment cooling fan
- Electrical compartment thermostat
- Electrical compartment thermocouple
- EMI filter
- Fuses
- Power supply, 24 VDC
- Relay (K6 - Voltage)
- Relay (K7 - EC Cooling Fan)
- Voltage sensor
- Wire harnesses
For information on accessing and removing parts,
see the Appendix.
Electrical Compartment Cooling fan
The oven has three fans across the top of the back
panel. The center fan cools the electrical compart-
ment. It is actuated by the cooling fan thermostat
when the temperature of the electrical compartment
reaches 120ºF (49ºC).
Electrical Compartment Thermostat
The cooling fan thermostat, located on the top elec-
trical panel, actuates the electrical compartment cool-
ing fan via the K7 cooling fan relay.
Electrical Compartment Thermocouple
The electrical compartment thermocouple is part
of the control board and measures the temperature
of the electrical compartment. If it is above 158 º F
(70 º C), an F6: EC TEMP fault will display. The
control board checks the electrical compartment
temperature once every 60 seconds.
EMI filter
The EMI filter helps suppress the amount of RF
interference emitted by the oven.
fuses
The F1 and F2 fuses are 12-amp, ATMR, class CC.
The F3 fuse is 20-amp, ATMR, class CC. The F1
fuse (via blue wire) and F2 fuse (via brown wire)
are designed to blow if an over-current situation is
encountered by the motor controller, any cooling
fan, either filament transformer, or power supply.
The F3 fuse is designed to blow in case of an over-
current situation encountered by the microwave
system (magnetron, high-voltage transformer, diode,
capacitor). It is also designed to blow if the monitor
switch opens before the primary or secondary switch
while the microwave circuit is energized.
Power Supply
The power supply outputs 24 VDC at 40 watts to
the control board and relays.
Relay - K6 Voltage
The K6 relay is a 240 VAC, 30 amp, three-pole,
double-throw, 24 VDC relay coil. Operational in
North America only, it switches between 208 and
240 VAC on the HV transformer and filament
transformer taps (depending on incoming voltage).
Through the voltage sensor, the oven defaults to the
240V position and switches to 208 if less than 222
volts is detected. 230V/400V international ovens and
all Japan models utilize the normally-closed (N.C.)
contacts of the relay (default position) to power the
microwave transformers.
Relay - K7: All Cooling fans
The K7 relay is a 240 VAC, 24 VDC coil, 20 amp,
sealed double-pole, double-throw relay. It switches
power to the center cooling fan when the electrical
compartment thermostat detects 120 º F (49 º C). See
page 40 for more details.
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Troubleshooting
