Component Test Procedure - Panasonic NN-CT577SEPG Service Manual

10 Component Test Procedure

• The inverter circuit operates at high voltages.
• Never attempt to measure the high voltage on the
inverter circuit.
• Before touching any oven components, or wiring,
always unplug the oven from its power source and
discharge the high voltage capacitors.
10.1 Primary latch switch, secondary
latch switch and power relay B
interlocks.
1. Unplug the lead wires from the contact terminals of
RY1, check the continuity across these terminals
using an ohm meter set to the lowest resistance
scale.
2. Unplug the lead wires to the primary latch switch
and secondary latch switch.
3. Test the continuity of each switch with an ohm
meter set to the lowest resistance scale. The test
must be completed with the microwave oven door
open and closed.
4. Normal continuity readings should be as follows.
Door Open
∞
Primary Latch Ω
Switch
∞
Secondary Latch Ω
switch
∞
Power relay B
Ω
10.2 Short switch and monitor circuit
1. Unplug the lead wires from the high voltage inverter
primary terminals.
2. Connect the test probes of the ohm meter to these
leads.
3. Test the continuity of the short switch with the door
open and the door closed using a ohm meter set to
the lowest resistance scale.
Door Open
Ω
Monitor switch
0
10.3 Magnetron
Continuity checks can only indicate an open filament or
a shorted magnetron. To diagnose an open filament or
shorted magnetron:
1. Disconnect the high voltage lead wires from the
magnetron input terminals.
2. Check the continuity across the magnetron filament
terminals, a good magnetron indicates a resistance
of 1 ohm or less.
Caution
Door Closed
Ω
0 (Close)
(Open)
Ω
0 (Close)
(Open)
∞
Ω
(Open) (Close)
Door Closed
∞
Ω
3. Check the continuity between each filament termi-
nal and the magnetron case, a good magnetron
indicates infinite
figure 16 Testing the magnetron
10.4 Push button keyboard
Check the continuity between the switch terminals on
the DPC AU, by tapping an appropriate pad on the key-
board and measuring the resistance across the corre-
sponding tracks on the ribbon cable.
10.5 Inverter power supply
DO NOT try to repair this inverter power supply.
Replace this inverter power supply as a unit.
15
∞
resistance.
Caution