Panasonic NN-SD372, Service Manual

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WARNING
1. High voltage is present at the output terminals of the High Voltage
Inverter (U) including aluminum heat sink during any cook cycle.
2. It is neither necessary nor advisable to attempt measurement of the
high voltage.
3. Before touching any oven components, or wiring, always unplug
the power cord and discharge the high voltage capacitors (see page
8).
7.1. Primary, Secondary Interlock
Switch & Power Relay RY1
1. Unplug lead connectors to Power Relay RY1 and verify
open circuit of the Power Relay RY1 1-2 terminals.
2. Unplug lead connectors to Primary Interlock Switch and
Secondary Interlock Switch.
3. Test the continuity of switches at door opened and closed
positions with ohm meter (low scale).
Normal continuity readings should be as follows.
Door Closed Door Opened
Primary Interlock Switch 0
Ω
(Close)
Ω
(Open)
Secondary Interlock Switch 0
Ω
(Close)
Ω
(Open)
Power Relay RY1
Ω
(Open)
Ω
(Open)
7.2. Monitor Switch
1. Unplug lead wires from Inverter Power Supply (U) primary
terminals.
2. Connect test probes of ohm meter to the disconnected
leads that were connected to Inverter Power Supply (U).
3. Test the continuity of Monitor Switch with door opened and
closed positions using lowest scale of the ohm meter.
Normal continuity readings should be as follows.
Door Opened Door Closed
0
Ω
(Close)
Ω
(Open)
7.3. Magnetron
Continuity checks can only indicate an open filament or a
shorted magnetron. To diagnose for an open filament or
shorted magnetron.
1. Isolate magnetron from the circuit by disconnecting the
leads.
2. A continuity check across magnetron filament terminals
should indicate one ohm or less.
3. A continuity check between each filament terminal and
magnetron case should read open.
7.4. DC fan motor
1. connection
2. Control wire of fan motor should accept PWM control.
Fan motor´s spin speed is controlled by this PWM siginal.
PWM frequency is from 18KHz to 30 KHz. If the PWM
control wire open, fan motor will spin at maximum speed.
7 COMPONENT TEST PROCEDURE
15
NN-SD372S