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 toattempt measu rement 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).

5.1. Primary, Secondary Latch

Switch interlocks & Power

Relay RY1

1. Unplug lead connectors to Power Relay RY1and verify
open circuit of the Power Relay RY1 1-2 terminals.
2. Unplug lead connectors to Primary Latch Switch and
Secondary Latch Switch.
3. Test thecontinuity of switchesat door openedand closed
positions with ohm meter (low scale).
Normal continuity readings should be as follows.
Door Closed Door Opened
Primary Latch Switch 0
Ω
(Close)
Ω
(Open)
Secondary Latch Switch 0
Ω
(Close)
Ω
(Open)
Power Relay RY1
Ω
(Open)
Ω
(Open)

5.2. Short Switch

1. Unplug leadwires from InverterPower 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 continuityof short switch with door openedand
closed positions using lowest scale of the ohm meter.
Normal continuity readings should be as follows.
Door Opened Door Closed
0Ω(Close) Ω(Open)

5.3. 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.

5.4. key board membrane

(Membrane switch assembly)

Check continuity between switch terminals, by tapping an
appropriate pad on the key board. The contacts assignment of
the respective pads on the key board is as shown in digital
programmer circuit.
5 COMPONENT TEST PROCEDURE
15
NN-SD452W/ NN-ST462M / NN-ST452W