Inverter Power Supply (U); Humidity Sensor - Panasonic NN-SD291S Service Manual

4.4.

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 Clock button once.
b. Press Timer button once.
c. Press Start button once.
d. Press Power Level button once.
5. Program oven at High power for 1 minute and press [Start]
button.
a. After approximately 23 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 Clock button once.
b. Press Timer button once.
c. Press Start button once.
d. Press Power Level button once.
the input current is
FAILURE CODE
Oven stops in 23
seconds after started.
11
5. Program oven at High power for 1 minute and press [Start]
button.
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.
4.5.

Humidity sensor

In order to determine if the humidity sensor function of the
digital programmer circuit is working, do the following test.
1. Program DPC.
a. Press Clock button once.
b. Press Timer button once.
c. Press Start button once.
d. Press Power Level button once.
2. Place a water load (100 ml) in the oven.
3. Press [Sensor Reheat] button.
4. Press [Start] button.
5. Humidity sensor detects steam after the [Start] button is
pressed.
6. The total amount of T1 cooking time appears in display
window. If the range of cooking time is 50 sec. ~ 2 Min.,
humidity sensor function is normal.
NN-SD291S / NN-SD291W
the input current
FAILURE CODE
0.4A Oven stops in 3
seconds after started.
is