Hi @trueseeker57
Most likely you're measuring the HV transformer primary winding when the wires are connected to the NC monitor switch.
This switch is used to short out the HV transformer in the event that the oven is operating and the door is opened by the user, shutting down the HV circuit and stopping the oven from continuing operating.
This is a safety feature designed to prevent harmful microwave radiation from escaping through an open door.
Here's the service manual for the oven.
On p.9 (of 35 pdf numbering) is the schematic diagram for the oven and on p.19/35 is the HV transformer test procedure. The HV transformer primary winding tests 0.2-0.4 Ohms, which for most DMMs (digital multimeters) appears as a short circuit.
What is the problem with the oven?
Hi @trueseeker57
Could be any of the other components in the HV circuit, i.e. transformer, capacitor, magnetron, the R2 relay on the control board or even the control board itself. The R2 relay completes the power path for the HV circuit to operate
See p.19 for how to test the HV components (the HV transformer primary appears to be OK from what you said, but this doesn't mean that the secondary winding or filament winding is OK)
See p.26 for the No microwave oscillation troubleshooting flowchart to view how to check the R2 relay.
If you do find the problem and it is a faulty part that needs to be replaced, here's a link to the parts list that is useful. Locate the wanted part in the list. This will show you the manufacturer's part number for the part. Search online for the manufacturer's part number only to find suppliers that suit you best.
Be safety aware when working in microwave ovens. The HV capacitor can store >5000V DC for months even if the power has been disconnected for this length of time. This amount of voltage can seriously injure you. The HV capacitor needs to be correctly discharged as soon as it can be accessed after the oven's cover has been removed and before commencing any further work in the oven