Measurements And Adjustments - Panasonic NN-A880WB Service Manual

See troubleshooting of the inverter circuit and magnetron on page 27 to determine if the inverter
power supply is still functioning.
10.7. Temperature Sensor
A temperature sensor is mounted on the rear of the oven. The resistance reading across the
thermistor should read 300K 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 connector from the
digital programmer circuit.
NOTE: If the microwave oven has been operated allow to cool to room temperature before
attempting to measure the thermistor resistance.
10.8. Humidity sensor and digital programmer circuit NN-A880WB
1. Check the resistance across the sensor heater terminals. Normal
cold resistance should read approximately 4.5 ohms.
2. Check the volatge across the sensor heater terminals. It should
read approximately 2.5VDC
3. In order to determine if the auto cooking by humidity sensor is
working, perform the following test. /
1. Place a water load (150cc) in the oven.
2. Press the auto reheat panel.
3. Press the start pad
4. The humidty sensor detects steam about 2 to 4 minutes after the
start pad has been pressed.
5. The auto cooking (T1) automatically switches to cooking time. (T2)
6. The remaining cooking time T2 appears in the display window. If
48s -1min 36 secs appears in the display , the humidty sensor
function is normal.

11. Measurements and Adjustments

Warning
- For continued protection against radiation hazard, replace only with
identical parts.
- When the 10 amp fuse is blown due to the operation of the short
switch, you must replace the primary latch switch and short
switch. Then follow the installation procedures below.
- Interlock switch replacement - In replacing faulty switches, be sure
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