Download Microwave Training.pps

The information provided in this training module covers the
operation and programming of the Viking Microwave units
NOTE: The information provided is subject to change without notice.
Viking Range Corporation – October 2008
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VMOS – DMOS
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Above is the wiring schematic for the VMOS – DMOS countertop
microwave unit. This drawing shows the oven disconnected from a power
source and with the door closed.
We will now connect the unit to a power source………
Open the door of the microwave. The Primary, Secondary and Door
Sensing Switch contacts open, while the Monitor switch contact closes.
If the Primary switch contact fails to open, then a direct short will result,
tripping the monitor fuse.
The control board senses the open Door Sensing Switch and activates the
RY-1 relay coil. The coil operates on 24 Volts DC.
This will allow a neutral path to the oven lamp.
With the RY-1 relay closed, we now have a neutral path for the oven
lamp.
Now lets close the door and program a cook cycle
Using the keypad on the microwave we will select
a 5 minute cook cycle.
Using the numbered keys, select 5-0-0 then hit
start
Using the cursor, select “Start/Touch On” below
With the door closed and a program selected, the control board will activate
the RY-1 relay. This will supply a neutral return to the lamp, turntable and
the fan motor.
The oven lamp will operate whenever the RY-1 relay is activated.
With the Primary Switch closed, we have line voltage to the turntable and fan motor.
The control board will activate the RY-2 relay. This will supply a neutral
return to the primary winding of the High Voltage transformer.
At the same time, line voltage is supplied to the primary side of the H.V.
transformer through the closed circuit in the Secondary Switch.
The secondary of the transformer is made up of two separate sections.
The filament section steps down the voltage to 3.5 Volts DC. This is required to
heat up the filament within the magnetron tube
The secondary of the transformer is made up of two separate sections.
The filament section steps down the voltage to 3.5 Volts DC. This is required to
heat up the filament within the magnetron tube
The filament will remain active as long as primary voltage is applied to the power
transformer.
Microwave HV systems use a process known as the
voltage doubling circuit.
The high voltage section produces 2300 Volts AC. During the first
positive half cycle, the voltage from the transformer travels the path
of least resistance, which is through ground, then through the rectifier
then into the capacitor where the charge is stored. This occurs at
1/150th of a second.
Peak charge in capacitor -2300 volts
During the second negative half cycle, the voltage from the
transformer travels into the capacitor. The transformer’s 2300 volts
and the stored capacitor voltage of 2300 volts are combined in
series, totaling 4600 VDC. Because of the rectifier, the discharged
voltage is applied to the magnetron tube. This occurs at 1/80th of a
second.
This cycle repeats 60 times per second at 60hz.
Total Voltage to tube -4600 volts
Advance
Red wire (com) – from noise filter
Orange wire (com) – to oven lamp
Brown wire (N.O.) – to fan motor
PRIMARY SWITCH
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