stefanfromingarö

Q: Macbook - problems to connect w external screen

I do a lot of presentations (Keynote) from Mac to external screens at events.

The new MacBook (12") is quite often having problems so I have to carry a MacBookAir as a back-up just in case.

Problems can be everything from no image at all, image with spikes and even two images (like 70% Keynote + 30% desktop).

It doesn't matter if I use HDMI or VGA. And yes, I know how to adjust resolution in settings Sometimes the problem is fixed by adjusting the resolution manually, but then the Macbook can jump back to the resolution that doesn't work by itself during the slideshow...

I believe the problem only occurs when I have to go through a device like a split or when there is lots of tech back stage.

Anyone else having problems like this with the MacBook?

Any ideas on whats wrong and how to solve it?

MacBook (Retina, 12-inch, Early 2015), OS X El Capitan (10.11.3)

Posted on Mar 21, 2016 1:53 AM

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Q: Macbook - problems to connect w external screen

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  • by paullywise,

    paullywise paullywise Aug 30, 2016 12:33 PM in response to Schendstok
    Level 1 (4 points)
    Notebooks
    Aug 30, 2016 12:33 PM in response to Schendstok

    Sounds like it's a widespread issue not related to particular assembly lines. I've got the m5 gold, and my brother's macbook is a 2015, mine's '16

  • by paullywise,

    paullywise paullywise Aug 30, 2016 5:08 PM in response to paullywise
    Level 1 (4 points)
    Notebooks
    Aug 30, 2016 5:08 PM in response to paullywise

    UPDATE:
    Out of curiosity, I grabbed this high speed HDMI 2.0 cable from Amazon. Lo and behold, it works on all my monitors and TV ports. It appears the hardware currently in the multiport adapter and/or computer require more throughput. Perhaps it's designed to have the monitor help power the feed.

     

    It works with the following big caveats:

    • I never get the menu icon for mirroring settings even with the pref's box checked
    • Don't know how long it will work for. I'm sure it'll stop as other users have experienced
    • On my TV, there's real cursor latency with all resolution settings
    • On my Asus PB287Q 4k monitor I had the blinking screen problem. An nvram reset fixed that... BUT
      • The overscanning is off, and there is no slider to fit the image to the screen like there used to be, so no way to fix it. Looks this way in all resolution settings (cropped menu bar and dock):

    IMG_0262.JPG

    Obviously the issues are far from fixed. Not least of which are Apple's advertising and documentation omitting the fact that a brand new, state of the art HDMI cable is required for extended displays to work at all. What's further baffling to me is that none of Apple's support -- all the way to the Engineering Team seem to know about these issues and specs.

     

    I've been working with and on Macs for over 15 years. I've never seen disconnects (no pun intended) like these before.

     

    Hope this helps.

  • by paullywise,

    paullywise paullywise Aug 30, 2016 5:40 PM in response to paullywise
    Level 1 (4 points)
    Notebooks
    Aug 30, 2016 5:40 PM in response to paullywise

    UPDATE 2:

    Was able to work around the overscan issue with a setting on my monitor.

  • by paullywise,

    paullywise paullywise Aug 31, 2016 12:25 PM in response to paullywise
    Level 1 (4 points)
    Notebooks
    Aug 31, 2016 12:25 PM in response to paullywise

    UPDATE 3

    I now have flickering/black screen problems as many in this thread have described. I'm now almost positive this is a power management problem whether due to software or hardware in the Apple multiport adapter, the computer, or both. Here's why:

     

    • Flashing screen increases when i load media heavy content on my monitor
    • When I plug in a USB device to the multiport adapter, my monitor flashes with increased frequency and intensity, depending on how power hungry the USB device is.
      • Charging my ipad eventually stabilized with flashing only occurring every 10 minutes or so
      • Running Duet extended monitor via the USB port on my ipad made my hdmi monitor flash every 2-5 minutes
      • Plugging in a usb 3.0 (unpowered) hub, with only my ipad plugged in, caused this indefinitely
  • by Dr.Mac.,

    Dr.Mac. Dr.Mac. Aug 31, 2016 1:27 PM in response to stefanfromingarö
    Level 3 (616 points)
    Aug 31, 2016 1:27 PM in response to stefanfromingarö

    My Analysis :  The Hot Plug Detect feature is a communication mechanism that makes the MacBook aware that it has been connected/disconnected to/from the External Display.  The MacBook with the Multiport Adapter takes some time to address these multiple Hot Plug Detect interrupts which cause:

    • External display to flicker
    • Various screen resolution and graphic profile retention issues

    No workaround is available for this issue (other than resetting the SMC/NVRAM).

  • by paullywise,

    paullywise paullywise Aug 31, 2016 3:08 PM in response to Dr.Mac.
    Level 1 (4 points)
    Notebooks
    Aug 31, 2016 3:08 PM in response to Dr.Mac.

    Thanks for the insights Dr.Mac. Any thoughts on why in this scenario different hdmi cables yield different results? I'd forgotten to mention in prev posts that the original hdmi cables i used were version 1.4b. Using those cables I couldn't get any image whatsoever on any of my monitors (said no input) except on the one 4k @ 60khz port. Apple's documentation says 1.4b is the minimum requirement. Only after getting an hdmi 2.0 with 3D support did it start to work but with the flashing issues.

     

    It also seems the Hot Plug Detect has to re-detect every so often, causing the display cut outs? So far this has continued for me every 5-20 minutes through a full day of work.

  • by marinerblue,

    marinerblue marinerblue Sep 1, 2016 8:01 AM in response to paullywise
    Level 1 (12 points)
    Notebooks
    Sep 1, 2016 8:01 AM in response to paullywise

    I've definitely found that HDMI cables make a difference, but don't solve the problem.  I started out with no-name cables, then tried Amazon Basics "high speed" HDMI cables. I subsequently bought the heaviest 1m cables that Monoprice sells (their "certified premium" high-speed HDMI and their flat commercial series 24AWG cables).  The beefy Monoprice cables have the 'blanking out' problem less often than the lower-specced (thinner conductor) cables from other places, but it's definitely still there.  (I should also note that these heavier-duty cables are significantly less flexible than the other HDMI cables I own, which makes positioning the AV Adapter more tricky.) Seems like the best medicine is a reboot in the morning.

  • by smthgelse,

    smthgelse smthgelse Sep 6, 2016 9:04 PM in response to smthgelse
    Level 1 (4 points)
    Sep 6, 2016 9:04 PM in response to smthgelse

    Update - I returned the second m7 macbook and exchanged it for an m5. I have not had issues with the m5 - I seen a very occasional flicker when working but they're so infrequent it doesn't interfere with work. However, work just bought me an m7 macbook (the m5 is a personal machine) and it has the flickering issue.

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