El Capitan Won't Detect External Display

[George Dawes]

I had a similar problem today . I used a display port to hdmi adaptor and that worked on a bang olufsen tv .

HDMI seems to have been seriously messed up by the latest 10.11.2 update.

It connected fine before the update.

 

[Paramita Mohamad]

I have had the same issues, and the solution of changing the cable (to mini displayport-display port) and not using the Apple connector works for me.

I have installed El Capitan in MacBook Air early 2015. My external monitor is Dell P2314H. After the installation, I tried to connected them via mini display port, Apple miniDP to DVI/HDMI/DP connector, and Dell's display port. MacBook Air no longer detected the monitor, and the monitor didn't register any video input from the computer. Tried resetting PRAM, SMC, unplugged and replugged the monitor's power cord, bypassing user log-in, all to no avail.

I tried to connect via another brand's miniDP to VGA connector, and it worked. I tried to connect my MacBook Air to my LG HDTV using the same Apple connector via HDMI, it worked. I figure out the culprit must be somewhere between Apple's mini displayport and Dell's displayport. I bought a cheap miniDP-DP cable locally (I live in Jakarta, Indonesia), reconnected the two, and it worked.

I have re-activated user log-in in MacBook Air, and it still works.

I hope this helps.

 

[riceforlife]

Since upgrading to 10.11.2, I've had a bunch of similar problems w/ my iMac 5K displays.

First, the 5K display on the iMac itself will not wake from sleep.

Second, even on a fresh boot, my two external monitors (Dell P2715Q and Dell U2713HM) are no longer recognized. I've tried unplugging monitor power cables, as well as PRAM and SMC resets.

Has anyone found a work around that doesn't involve buying new miniDP-DP adapters?

 

[riceforlife]

Ah, finally solved it!

1. I updated to 10.11.3 beta. But, I don't think this was the solution, as upon booting up, I still didn't have my external displays working.
2. After the update, I tried unplugging all non display devices from my iMac (i.e. USB/stereo output). Afterwards, my external displays worked and the iMac display woke from sleep!

 

[gustavonv]

When my last cable broke i decided to buy a dvi-hdmi adapter.

But it don't work in any way. "HDMI on thunderbolt adapter", directly on "hdmi port".

In the console I can see that my monitor was detected.

In my xbox, adapter run fine, DVI-HDMI, the problem is something on mac.
In when mac try trigger the monitor under HDMI.
......

with an 'voltimeter' i can identify, the OSX dont send any energy on "ground" with my new hdmi adapter.

with a tiny cord making a "jumper", problem solved.
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A certified cable certainly solve the problem, but for a $ 1 adapter I can use any HDMI cable.

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Pics of "Gambiarra"
https://twitter.com/gustavoneves/status/751119083924488192