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.

  • Except for a cable issue, I can't think of anything.
    – JMY1000
    Jan 6, 2018 at 17:37

2 Answers 2


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.


Sounds like a hardware issue.

Try finding the cause by testing it on either Thunderbolt 3 port on your iMac, on all the HDMI ports on the TV (especially test it with port 1 that you have already identified is working), test with a different HDMI cable - and ultimately test with a different adapter if possible.

In my experience the setups where you have an adapter and then an HDMI cable are more error-prone than those where you have a cable directly from Thunderbolt 3 (USB-C connector) to HDMI.

  • Sorry for delaying I was in the longlasting business trip and didn't have access to my Mac. I have the cable connecting the iMac straightforward from the Thunderbolt 3 (USB Type-C) to the HDMI port on the TV without extra adapters. And I've reset NVRAM and SMC but with no luck. The only option I've not tested yet is another cable.
    – treegor
    May 21, 2018 at 18:25
  • Maybe it's a matter so I want to mention here that when I connect ny Mac to the TV it displays the message on the black screen telling me that resolution isn't supported.
    – treegor
    May 21, 2018 at 18:36
  • Quite important information :-) You have selected a too high resolution for the external monitor. In the System Prefences under Display, choose to Gather Windows so that you can change the preferences for the TV on the main display. Set it to a lower resolution and hopefully things will start working.
    – jksoegaard
    May 22, 2018 at 9:52
  • Thanks for the reply but I have to admit that macOS doesn't detect second monitor at all consequently Gather Windows button unavailable in Display preferences
    – treegor
    May 22, 2018 at 10:37
  • Sounds very much like a cable failure :-) Try with a different cable.
    – jksoegaard
    May 22, 2018 at 10:43

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