Got new USBC to HDMI cable now have an issue

[joeg679]

I was using a cheap Amazon cable to connect my macbook pro to an external monitor, but I was getting an issue where the screen would go black and I'd have to unplug then plug back into my macbook. I got a new cable today and plugged it in and it's not working properly. Firstly, on the touchbar, I get a 'display connected' message and it gives me the option to make the other monitor a mirror or extended desktop. With the old cable I didn't get this. Secondly, I'm getting weird lines - they don't show up in a screenshot, only when I take a pic of the external monitor. The main laptop screen is fine. Any ideas? Thank you

 

[Lifeisabeach]

Well with regards to the message you get with the new cable about the display being connected, that sounds normal and suggests the cheap Amazon cable was cheap for a reason. As for those lines you are getting... that's almost certainly some sort of signal noise, or artifact from the display trying to reproduce a resolution that it doesn't support. You wouldn't see this in a screen cap.

Can you tell us what exact model display you have, and what exact cable you picked up? Also, what resolution have you set for the external display. Are you mirroring or using is as an extended desktop?

 

[Randy B. Singer]

I was using a cheap Amazon cable to connect my macbook pro to an external monitor...

Whenever I hear this, the first thing that comes to mind is whether you simply got a USB-C cable, or whether you got a cable that supports Thunderbolt? If you have a fairly recent Mac, and a fairly recent high resolution monitor, you need an adapter cable that supports Thunderbolt. This one is reasonably priced and works well:

USB C to HDMI Cable 6ft, Anker Type C to HDMI Adapter Cable 4K 60Hz for MacBook Pro 2020, iPad Pro 2020, Samsung Galaxy S20/ S10, Dell XPS 13/15, and More [Thunderbolt 3 Compatible]

$22

https://www.amazon.com/dp/B08DLK2FD9/?tag=macforums0e4-20

 

[Slydude]

That's a good question, Randy. I sometimes forget that there's a difference between the two types of cables.

Since my 2008 MacBook Pro seems to have finally given up the ghost, I'll have to start paying closer attention to some of the quirks in the newer connectors/ports.