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’sAC power supply cord isunplugged
from the wall outlet, unplug the 2 pin H.V. connector CN703
from the magnetron tube.
2. Place 1liter ofwater load intooven cavity.
3. Plug inthe oven’sAC power supplycord intooutlet.
4. Program DPC.
For SD452W model
a. Press Clock button once.
b. Press Timer button once.
c. Press Start buttononce.
d. Press 1000W/600W button once.
For ST462M & ST452W models
a. Press Timer pad twice.
b. Press Start pad once.
c. Press Micro Power pad once.
5. Program ovenat Highpower for1 minute andpress [Start]
pad.
a. After approximately23 seconds,oven stops operating.
b. During oven operation, the input current is
approximately 0.5 to 1A. If both a and b are OK,
proceed to test 2.
INPUT CURRENT FAILURE CODE
Unplug CN703 0.5 to 1A Oven stops in 23
seconds after started.
Test 2
Continued from Test 1
1. Unplug theoven’s ACpower supply cordfrom outlet.
2. Unplug 3pin connectorCN701. CN703remains unplugged.
3. Plug inthe oven’sAC power supplycord intooutlet.
4. Program DPC.
For SD452W model
a. Press Clock button once.
b. Press Timer button once.
c. Press Start buttononce.
d. Press 1000W/600W button once.
For ST462M & ST452W models
a. Press Timer pad twice.
b. Press Start pad once.
c. Press Micro Power pad once.
5. Program ovenat Highpower for1 minute andpress [Start]
pad.
a. After approximately3 seconds,oven stops operating.
b. During oven operation, the input current is
approximately 0.4A.
INPUT CURRENT FAILURE CODE
Unplug CN701 0.4A Oven stops in 3
seconds after started.
If both a and b check OK, the Inverter Power Supply (U)can be
determined to be OK.
5.6. Temperature thermistor
The thermistor that is attached to the magnetron detects the
temperature of the magnetron and will stop magnetron
operation when overheating is detected. A normal thermistor´s
resistance is 35KΩto 110KΩfor an ambient temperature range
of 10-30 degree C.
If the resistance reading is out of the range stated here, the
thermistor is detective and must be replaced.
It is also possible to display thermistor level by taking the
following steps.
For SD452W model
1. Program theDPC intoTEST MODE(Plug-in oven→press
Clock button once →press Timer button once →press
Start button once →press 1000W/600W button once).
2. Program oven at Standing Timefor 1 minute and press
[Start] button.
3. Press Sensor Reheat once, the thermistor level reading
will shown on the display.
The normal reading should be in the range of 16-230.
For ST462M & ST452W models
1. Program theDPC intoTEST MODE(Plug-in oven→press
Timer pad twice →press Start pad once →press
Micro Power padonce).
2. Program oven at Standing Timefor 1 minute and press
[Start] pad.
3. Press Reheat twice, the thermistor level reading will
shown on the display.
The normal reading should be in the range of 16-230.
16
NN-SD452W/ NN-ST462M / NN-ST452W