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-9970,
NE-9970C
-9870,
NE-9870C
DESCRIPTION OF OPERATING SEQUENCE
1. Variable power cooking control
The coil of power relay C is energized intermittently by the digital
programmer circuit, when the oven is set at any power selection ex-
cept for High power position. The digital programmer circuit controls
the ON-OFF time of power relay C contacts in order to vary the output
power of the microwave oven from "Warm" to "High" power.
One complete ON and OFF cycle of power relay C is 22 seconds.
The relation between indications on the control panel and the output
of the microwave oven is as shown in Fig. 5.
NOTE: The ON/OFF time ratio does not correspond with the percen-
tage of microwave power since approximately 2 seconds are
required for heating of magnetron filament
2. Cyclic defrost
When Defrost power and defrosting time is selected and Start pad is
tapped:
(B) During each defrosting period, power relay C is energized for 9
seconds and de-energized for 13 seconds by DPC. (See Fig. 7)
(C) During standing periods, power relay C is always open resulting in no
microwave power.
ae
NOTE: Defrost time selected is converted into seconds by the DPC but
display will show selected time in minutes and seconds as prog-
rammed. The total number of seconds is divided Into 8 time
periods. The remainder (seconds not equally divisible by 8) are
added to the last standing time period.
Example 1: If defrosting time is selected for 2 minutes 56 seconds, each
operating period will be as follows
: (See Fig. 8)
2 minutes 56 seconds = 176 seconds
176/8 = 22
Example 2: If defrosting time is selected for 5 minutes, each operating
period will be as follows : (See Fig. 9)
5 minutes = 300 seconds
300/8 = 37 and remainder is 4 seconds.
The 4 seconds is added to the last time period.
NOTE: When defrosting time is selected for not more than 7 seconds,
the power relay C will not be energized at all.
OUTPUT POWER
INDICATION | AGAINST
ON, OFF TIME ON
HIGH POWER
POWER RELAY C
138,
9s
433
! 2 :
:
S
"1.2,
93
'<I
4s
us
Low
8/22 (190W)
°
OFF
Defrost
Approx
Please tefer to description
110W
of cyclic defrost.
Fig. 5
TOTAL
DEFROSTING
TIME
18
-
TB
Ta
TB
18
18
T8
18
7
Fig. 6
ONE DEFROSTING PERIOD(T/8)
a
7
2MIN
S6SEC(176SEC)
Fig. 8
SMIN
(300SEC)
LAS!
STAgr
8G 418)
Fig. 9
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