TRANS H.V;SHV-U1870C,120 DE26-00126A

Hi Gerald, thank you for the question. In transformers, we have 3 different windings. To test the transformer, you may set the multimeter on ohm setting, and check the continuity of each winding separately. If there is no continuity in any of the coil, you will need to replace the transformer. To test the magnetron, turn the dial of the multimeter to the smallest resistance listing so you get the most accurate reading from the magnetron. Connect the leads of the multimeter to the prongs of the magnetron. Look at the multimeter’s screen and take note of the reading. If the resistance stays below 1 ohm, then the electric filament inside the magnetron functions properly. If you get a higher reading or if the screen reads “OL”, then the magnetron is faulty and should be replaced. We hope this information helps!