11
CIRCUIT DESCRIPTION
1. When the food is placed in the oven cavity and door is closed.
• The contact of the interlock monitor switch is opened(NO).
• The contacts of the primary interlock switch and secondary interlock switch are closed.
2. When the timer is set to the time desired.
• The contact of the timer switch is closed.
• Oven lamp turns on.
• 230V AC is applied to the hogh voltage transformer.
• Turntable motor start rotating and glass tray rotating.
• Fan motor rotates and cools the magnetron by blowing air.
• Timer motor operates and points to passing cooking time.
• 3.3 Volts AC is generated from the filamente winding of the high voltage transformer. This filament voltage is
applied to the magnetron to heat the magnetron filament through two noise preventing ckoke coils.
• A high voltage of 2000 Volts Ac is generated in the secondary of high voltage transformer and this secondary
voltage is increase by the action of the diode and the charging of the high voltage transformer and this
secondary voltage is increased by the action of the diode and the charging of the high voltage capacitor. This
resultant D.C voltage is then applied to the anode of the magnetron. As shown in Fig. 2 the first half voltage
capacitor. Current flow is in the direction of the dotted-line during the second half cycle, the voltage produced by
the transformer secondary, and the charge of the high voltage capacitor are combined and applied to the
magnetron as shown by the solid line so that oscillations begins.
The disturbance wave generated by the magnetron is prevented by the choke coils of 1.5µH, filter capacitors of
500pF and the magnetron’s shielded case so that TV and radio programs are not impaired by noise.
TM
TM
CL
GM
FM
CL
GM
FM
12A Fuse
Primary
Interlock
Switch
Timer
Switch
COM
NC
NO
Interlock
Monitor
Switch
Secondary
Interlock
Switch
Timer Motor
Cavity Lamp
Geared Motor
Fan Motor
Fig. 1
