Advertisement
4. Membrane key board (membrane switch assembly)
Check the continuity of the membrane key pads. Connect a meter
or continuity tester to the appropriate tracks on the membrane ribbon
cable, press the coresponding keypad on the escutcheon sheet.
The membrane
key pad drawing can be found on the digital
programmer schematic at the back of this manual.
5. Oven temperature thermistor
The resistance reading across the thermistor should read 300K
ohm to 1500K ohm within a temperature range of 10 to 30 degrees
centigrade.
This would be the temperature range within a kitchen
environment.
If the resistance measured is outside this range the
thermistor is defective and should be replaced.
NOTE: When measuring the resistance of the thermistor disconnect
the 4 pin connector from the digital programmer circuit.
NOTE: }f the microwave oven as been operated allow to cool to
room temperature before attempting to measure the thermistor
resistance.
6. Diode
(A) Disconnect all leads from the diode.
(B) Set the meter to the highest ohm scale
(C) Measure the resistance between the diode terminals in both
directions.
(D) Anormal diodes resistance will be infinite in one direction and several
hundred K ohms in the other direction.
(E) The meter must be operated by a 9 volt battery or greater.
7. Protector diode
(A) Disconnect all leads from the protector diode.
(B) Set the meter to its highest ohm scale.
(E) Any resistance reading indicates a faulty protector diode.
(F) The meter must be operated by a 9 volt battery or greater.
8. Humidity sensor and digital programmer circuit.
NN-C897WB
NN-C897CB
(A) Check the resistance across the sensor heater terminals.
Normal cold resistance should read approximately 4.5 ohms
(B) Check the voltage across the sensor heater terminals.
It should
read approximately 2.5 VDC
(C) In order to determine if the auto cooking by humidity sensor
is
working or not, perform the following test.
(1) Place a water load (150 cc) in the oven
(2) Press auto reheat panel
(3) Press start pad
(4) The humidity sensor detects steam about 2 to 4 minutes after the
start pad has been pressed.
(5) Auto cooking (T1) automatically switches to time cooking. (T2).
(6) The remaining cooking time T2 appears in the display window. if 48
- 1.36 appears in the display , The humidity sensor function is normal.
NIN ROtSTANU SHEN IN Orso rAGis)
NINE
OtST MAU SEEN IN Oss Aels:
NOTE: OHMMETER SHOULD HAVE A MINIMUM OF A 9VOLT
BATTERY
REVERSE
SEVERAL HUNDRED K ohm
INFINITY
HIGHEST OHM
SCALE
FORWARD
REVERSE
INFINITY
INFINITY
HUMIDITY
SENSOR
Advertisement
