Component Test Procedure - Panasonic NN-T793SF APH Service Manual

CAUTION
1. High voltage is present at the high voltage terminal of
the High Voltage Inverter (U) including aluminum heat
sink during any cook cycle.
2. It is neither necessary nor advisable to attempt mea-
surement of the high voltage.
3. Before touching any oven components, or wiring,
always unplug the oven from its power source and
discharge the high voltage capacitors.
1. Primary Latch Switch, Secondary (Secondary Latch
Switch and Power Relay B) Interlocks.
(A) Unplug the lead connectors to Power Relay B and verify continuity
of the power relay B 1-2 terminals.
(B) Unplug lead connectors to Primary Latch Switch and Secondary
Latch Switch.
(C) Test the continuity of switches at door opened and closed positions
with ohm meter (low scale).
Normal continuity readings should be as follows.
Primary Latch Switch
Secondary Latch Switch
Power Relay B
2. Short Switch & Monitor
(A) Unplug lead wires from Inverter Power Supply (U) primary terminals.
(B) Connect test probes of ohm meter to the disconnected leads which
were connected to Inverter Power Supply (U).
(C) Test the continuity of short switch with door opened and closed
positions using lowest scale of the ohm meter.
Normal continuity readings should be as follows.
Door Opened
Ω
0
3. Magnetron
Continuity checks can only indicate an open filament or a shorted
magnetron. To diagnose for an open filament or shorted
magnetron.
(A) Isolate magnetron from the circuit by disconnecting the leads.
(B) A continuity check across magnetron filament terminals should
indicate one ohm or less.
(C) A continuity check between each filament terminal and magnetron
case should read open.
ANTENNA
COOLING
FIN
MAGNETRON
CASE
HIGHEST
OHM
SCALE
4. Membrane key board (Membrane switch assembly)
Check continuity between switch terminals, by tapping an appropri-
ate pad on the key board. The contacts assignment of the
respective pads on the key board is as shown in digital programmer
circuit.

COMPONENT TEST PROCEDURE

NEW. H.V.
Door Closed Door Opened
Ω Ω
0 (close) (open)
Ω Ω
0 (close) (open)
Ω Ω
(open) (open)
Door Closed
Ω
ANTENNA GASKET
0Ω-1Ω
RX1
SCALE
FILAMENT
TERMINALS
04-031M
5. Inverter Power Supply (U)for USA only
DO NOT try to REPAIR this H.V. Inverter power supply
(U).Replace as whole H.V. Inverter(U) Unit.
DO NOT TOUCH (HOT/HIGT VOLTAGE)
HEAT SINK
CHOKE COIL
CURRENT
TRANSFORMER
RESISTOR
SAND BAR
PCB
DANGER HIGH VOLTAGE
Test if failure codes of H97 or H98 appears by doing the following
procedure. It is recommended to use an AC line input current
Ampere meter for testing.
Test 1
A. Program DPC.
1. Tap Clock
2. Tap TIMER
3. Tap START
4. Tap POWER LEVEL
B. Place 1 liter of water load into oven cavity.
C. Unplug 2 pin H.V. lead wire connector CN703 from magnetron
tube.
D. Program oven at High power for 1 minute and press start.
1. After approximately 15 seconds, oven displays H98 and
stops oven.
2. During oven operation, input current is approximately 1.0
to 1.7A. If both 1 and 2 are OK, please proceed to test 2.
INPUT AMPERE
Unplug CN703
.
Test 2.
Continued from Test 1
A. Unplug 3 pin connector, CN701
B. Set oven at High power for 1 minute and start.
1. After approximately 27 seconds, oven displays H97 and
stops oven.
2. During oven operation, input current is approximately 0.4
to 0.8A
INPUT AMPERE
Unplug CN701
If both 1 and 2 are OK, the Inverter Power Supply (U) can be
determined OK.
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HIGH BOLTAGE
TRANSFORMER
DO NOT TOUCH 4
FAILURE CODE
1.0 to 1.7A H98
FAILURE CODE
0.4 to 0.8A H97
FILM CAPACITORS
VARISTOR
PRIMARY WINDINGS
SECONDARY
WINDINGS
HIGH VOLTAGE
DIODES