I googled the SMH9187ST model number for the shut down problem. I found a you tube video that showed how to repair the same issue. I was able open up the microwave without removing it from above the range. I first unplugged the microwave. Then, I unscrewed two Philips screws from the front top of the case. This allowed the top plastic grill to slide to the left and then off. This exposed the one screw that secured the front panel. After removing that screw, the front panel slid up, and I was able to tilt it forward. I did a visual inspection. I found that the nylon insulation on one of the spade connectors had a scorch mark. This spade connector was attached to Temperature Cut Out (TCO) thermal fuse. I measured the impedance across that TCO. It was 45 ohms. According to the schematic, I found online, that TCO should be normally closed (less than 1 ohm). I found the parts breakdown online. There was second TCO in the same vicinity. Since the parts illustration was did not clearly identify which of the two part numbers went with which device, I decided to buy replacements for both TCO's. I ordered the TCO's on the weekend. They were shipped Monday, and I received them Tuesday. The faulty part was marked "KSD-120LC 0". One of the parts I received had the same marking. This corresponded to the part in the bag marked with the manufacture's part number DE47-20059B. After swapping out this part, I reassembled the microwave. My Samsung microwave is working fine now.