Robert J Matthews , NC November 01, 2020 Appliance: Samsung Microwave SMH9187ST/XAA Samsung Microwave Smh9187st/Xaa / : Microwave powered on whenever door was closed and continued to "cook" even after pressing stop. I put a cup of water in it to verify is was cooking and not just making a noise. How to replace Assy Pcb Parts;Smh918. Checked all the micro switches associated with the door. Since they were all good, I replaced the electronic control board. Do-It-Yourself Rating: Repair Time Estimate: 30-60 minutes