Inverter NN-T551CB, Service Manual

Page: 34 / 63

3. Test the continuity of the switches with the door open and closed with an ohm
meter on the lowest scale.
Normal continuity readings should be as followed.
Door Open Door Closed
Primary Latch
Switch infinite
(Open)
0 (Close)
Secondary
Latch switch infinite
(Open)
0 (Close)
Power relay B infinite
(Open)
infinite
(Close)
9.2. Short Switch and Monitor Circuit
1. Unplug the lead wires from the HV 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 the lowest ohm scale.
Door Open Door Closed
Monitor switch 0 infinte
9.3. Magnetron
Continuity checks can only indicate an open filament or a shorted magnetron. To
diagnose an open filament or shorted magnetron.
1. Isolate the magnetron from the circuit by disconnecting the HV leads.
2. A continuity check across the magnetron filament terminals should indicate one
ohm or less.
3. A continuity check between each filament terminal and the magnetron case should
read open.