Panasonic NN-ST340M - Microwave Component Test Procedures; Latch Switch Interlocks Testing; Short Switch and Monitor Testing; High Voltage Transformer Testing

WARNING
1. High voltage is present at the high voltage terminal of the high
voltage transformer 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 capacitor (see page 9).
7.1. Primary, Secondary Latch
Switch Interlocks
1. Unplug lead connectors to Primary Latch Switch and
Secondary Latch Switch.
2. Test the continuity of switches at door opened and closed
positions with ohm meter (low scale).
Normal continuity readings should be as follows.
7.2. Short Switch & Monitor
1. Unplug lead wires from H.V.transformer primary terminals.
2. Connect test probes of ohm meter to the disconnected
leads of the H.V. Transformer.
3. 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.
7.3. High voltage transformer
1. Remove connectors from the transformer terminals and
check continuity.
2. Normal (cold) resistance readings should be as follows:
Secondary winding......................... Approx. 195 Ω~240 Ω
Filament winding.............................. Approx. 0 Ω
Primary winding................................. Approx. 0 Ω ~3 Ω
7.4. High voltage capacitor
1. Check continuity of capacitor with meter on highest OHM
scale.
2. A normal capacitor will show continuity for a short time, and
then indicate 9MΩ once the capacitor is charged.
3. A shorted capacitor will show continuous continuity.
4. An open capacitor will show constant 9MΩ.
5. Resistance between each terminal and chassis should be
infinite.
7.5. 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 COMPONENT TEST PROCEDURE
15
NN-ST340M / NN-ST340W / NN-SM330M / NN-SM330W / NN-SM320M