How to set up second screen in iMac 2017 with macOS 10.12.6 Sierra? I have a new iMac 4k 21.5" (2017) running under macOS Sierra 10.12.6 and featuring 2 Thunderbolt 3 (USB-C) ports for the connection to additional displays.

I'm attempting to connect this Mac to my 6 years old Samsung HD TV (32" 1080p (UE32C)) but with no luck. My TV has 4 HDMI ports, port 1 is connected to Apple TV and works quite well, the rest 3 ports had been used to hook up my Mac over an EZQuest cable.

I supposed that connection process should be trivial, you only have to connect the cable to the mac and to the TV than open system config tool and set up monitor in the screen config section but I failed. I have only got the black screen on the TV and second screen doesn't appear in the macOS config utility.

I would appreciate if someone suggest me where is the root of problem except the broken cable obviously.
I solved the problem finally, today I bought cheap Lenovo adapter and it works well. Previously unfair ad drove me to make the wrong decision to buy incompatible adapter. My brand new EZQuest cable working well with old MacBook 12" 2015 refuses to work with iMac 21.5" 4K 2017.