Inverter Power Supply (U); Temperature Thermistor - Panasonic NN-SD698S Service Manual

5.5.

Inverter power supply (U)

DO NOT try to REPAIR H.V. Inverter power supply (U).
Replace complete H.V. Inverter(U) Unit.
WARNING: HIGH VOLTAGE
Test if failure codes H95, H97 or H98 appear when performing
the following procedure. It is recommended to use an AC line
input current ammeter for testing.
Test 1
1. With the oven unit's AC power supply cord is unplugged
from the wall outlet, unplug the 2 pin H.V. connector CN703
from the magnetron tube.
2. Place 1 liter of water load into oven cavity.
3. Plug in the oven's AC power supply cord into outlet.
4. Program DPC.
a. Press Timer/Clock pad twice.
b. Press Start pad once.
c. Press Power Level pad once.
5. Program oven at High power for 1 minute and press [Start]
pad.
a. After approximately 37 seconds, oven stops operating.
b. During oven operation,
approximately 0.5 to 1A. If both a and b are OK,
proceed to test 2.
INPUT CURRENT
Unplug CN703 0.5 to 1A
Test 2
Continued from Test 1
1. Unplug the oven's AC power supply cord from outlet.
2. Unplug 3 pin connector CN701. CN703 remains unplugged.
3. Plug in the oven's AC power supply cord into outlet.
4. Program DPC.
a. Press Timer/Clock pad twice.
b. Press Start pad once.
c. Press Power Level pad once.
the input current is
FAILURE CODE
Oven stops in 37
seconds after started.
15
5. Program oven at High power for 1 minute and press [Start]
pad.
a. After approximately 3 seconds, oven stops operating.
b. During oven operation,
approximately 0.4A.
INPUT CURRENT
Unplug CN701
If both a and b check OK, the Inverter Power Supply (U) can be
determined to be OK.
5.6.

Temperature thermistor

These sensor monitors the heat produced by the heater circuit
and maintains the magnetron temperature which user had
selected. Normal room temperature 10°C to 30°C, the reading
across the temperature thermistor should be as follows.
TEMP
100°C
25°C
If the resistance reading is out of the range stated here, the
thermistor is detective and must be replaced.
NN-SD698S / NN-ST678S / NN-ST658W
the input current
FAILURE CODE
0.4A Oven stops in 3
seconds after started.
MAGNETRON THERMISTOR
30-60KΩ
700K-1.5MΩ
is