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Model A1311 / Mid 2010 / 3.06 & 3.2 GHz Core i3 or 3.6 GHz Core i5 Processor

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How to use iMac only with external monitor

Hello excellent iFixit community,

I recently diagnosed a client's iMac as having a failed LCD panel. I mentioned to him he could use it only with an external display, and he accepted this solution, at which point I disconnected the LVDS cable, backlight power cable, and V-SYNC cable. I left the LCD temperature sensor cable connected.

This setup worked for me in the shop with an external, but apparently didn't work for him when he took it home and tried it several weeks later.

He brought it back into our shop, and I confirmed my external display no longer showed an image - either during boot or at the user login screen, even after resetting PRAM and the SMC. I opened it up, connected the VSYNC cable for the heck of it, and the external worked - it displayed the boot screen.

Strange.

I disconnected the VSYNC, and tried again. The external monitor still worked - even though this was exactly the same configuration that didn't work 5 minutes before.

Was I wrong to suggest that disconnecting his internal display would provide a reliable solution? If not, does anyone understand what's going on?

Beantwoord! Bekijk het antwoord Dit probleem heb ik ook

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Why don't you leave the connections active?

I suspect the lack of power while in transit is the cause here.

Update (10/17/2016)

While you can run the system with the internal display disconnected for diagnostics. I've never tried running a system like what you are doing here. Is finding a workable LCD screen that costly?

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You may have misunderstood my post. The client has a failed LCD and opted not to replace it, but wants to continue using his machine with an external display.

In my experience, externals displays don't show an image until the system's booted to the user login screen. Since I'd noticed that disconnecting the internal display forces the system to display even the boot sequence on the external, I suggested this to the customer.

However, my results have been mixed, so I was asking for other experienced techs' advice.

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No, I followed you here. The focus was on the aesthetics of having the internal screen not active during the boot up Vs the external.

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We're a pretty down-to-earth (sometimes crunchy-granola-y) shop and offer low- or no-cost solutions as an option when we think they would address the customer's needs. I'd offered this as a no-cost/no-repair solution to the customer... but if it doesn't work reliably, then it's definitely not a solution.

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Thats fine ;-} Cheap is good! Sadly, I don't know of any way around this.

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I realize this is old, but I figured I would comment in case anyone else is running across this. Just like Dan said, there is no way to force the secondary monitor to act as the primary on startup while the internal display cable is still connected.

Disconnecting the internal display cable is a reliable way to force the secondary monitor, but I would strongly suggest taping the pins on the display cable with electrostatic tape to be safe.

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Maybe we're talking about something different , I'm typing this text on an imac with a dead lcd screen and plugged into my 28 inch Asus monitor...I don't reset it everytime, works just fine this way until I replace the Lcd display... I use a mini display port to HDMI... It's a quick fix for anyone who loses their display at a bad time.

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I am trying to start iMac A1311 on external monitor only because the LVDS connector is damaged. I can hear the boot chime but the external monitor shows nothing. I am connecting external monitor via mini DP/thunderbolt port to a DVI adapter. Any suggestion here?

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Hi @thomaslhuang i got the exact same problem, did you solve it?

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I have the same issue going on with my 2013 iMac, whose display has passed on. I was using an old Apple display as a 2nd screen but not set up as the log-in screen. I did a bunch of things suggested here and elsewhere, and even saw that there is a shortcut for forcing the displays to mirror : Cmd+F1 (or Fn+Cmd+F1 (though I haven’t tried this). Instead, I tried connecting to the dead-display iMac via screen sharing. Voila! The login screen came up on that computer. I was able to log in, went to preferences/displays/mirror displays. Now I am able to work on this computer again, albeit with a single display.

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Use command +F1 to boot to external display on start up.... Four out of five voices agree.

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Sorry guy that only sets the external monitor into Mirror mode on what the internal is displaying. Every time you restart the system you would need to reset it.

Here's a full listing of all of the keyboard short cuts you can use: Keyboard shortcuts

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I have tried it. Use it specifically at logging in, not upon booting or starting up (it doesn't work then).

It works fine: once you see the background screen, if you don't have the log-in screen on your external monitor, you just hit <command>-F1 for mirroring. I am happy with that solution. Even though my internal LCD is 5K retina, I have tested it OK with FHD external monitor. Computer: late 2014 iMac retina 27".

I am trying this solution just in case I break my LCD when I have to replace my internal HDD that went bad. Too bad apple thought thin edges was important.

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Update: For some reason, this only works with an APPLE keyboard. I typically use an external MS keyboard. I can see, using the apple keyboard viewer, that I am generating <command>-F1, but it does not generate the screen-mirroring toggle that the same combination produces on the apple keyboard. On the apple keyboard, the key sequence never makes it to the keyboard viewer; rather it is intercepted and changes the screen mirroring before the keyboard viewer sees it.

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I have a similar issue. The backlight has failed on my mid-2010 iMac 27”. I now have an ultra HD 35” widescreen monitor connected vie display port and that works fine. The only problem is that sometimes I will open an app but it will appear on the iMac screen instead of the external one. This means I cannot see the app!

What I need is a way to make the external screen the ONLY one and not as part of an extended desktop to the internal iMac screen. I have yet to find a way to do this so if anyone knows a way please let me know?

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You could set it to mirrored display, instead of extended, therefore your external would mirror the exact same thing as the internal monitor.

Failing that, I had the same issue as you and could pretty much get by, until the internal HDD failed. After that, I had to reinstall the OS which sadly only boots on the main screen. You might have some luck just unplugging the LVDS cable, which basically unplugs the internal screen, thus it will make the external the main screen instead.

This also worked for me for about 2 years, until recently, the iMac wouldn't boot, if I didn't have the LVDS plugged in. At this point I thought all was lost, as there was noway to force the OSX installation onto the external screen, until I just put a Windows 10 HDD in the iMac. Now my iMac runs Windows 10 natively and no more issues (as the boot screen appears on my External screen).

I recommend setting the display to Mirrored, and if that doesn't work, unplug the LVDS.

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I have a 2013 iMac that has a current working internal screen with 2 x 27” ACD (MDP) for a 3x monitor setup for work. However the stand has the issue where broken clips inside can’t keep the unit upright and taking it apart just for fixing the stand is not exciting enough for me to want to open it up.

I love my iMac but I am very intrigued on doing something like this since many won’t and it doesn’t bother me one bit to experiment on.

This is for having something different but as a “mod and learn from experience”

I have an additional 27” ACD so I would still retain the 3x monitor setup.

There are 2 approaches I’d like to choose from in an attempt to go with all external monitors on my desk because I’m a weirdo:

  1. Gut the iMac and put the components in a slim pc case or a rack mount case to mount under the desk:
    • Yes it doesn’t make sense, I understand nothing will fit correctly, but being how slim the components are, a slim open case to keep the comments ventilated with maybe an additional fan might suffice as this would no longer be upright to allow heat to escape as when the iMac is vertical as designed.
    • Maybe JB welding motherboard standoffs where needed on the new case to where the components would bolt onto and keep the same configuration, down to the speakers.
  2. Remove the built-in screen and the stand and mount it under the desk as is with flush under the desk. This will basically keep everything in place where I would just make some brackets to hold the iMac up, with space to let heat dissipate.

And yes before anyone says anything, I can sell it as is, put the money to something else like a Mac Mini or MBP, but where is the fun in that when we can tinker?

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I have a 2015 27" iMac with a display that recently stopped working. Since I upgraded to a SSD last year it's running super fast, I'd like to continue using it. Currently it's in screen mirror mode connected to an external monitor.

I really like the idea of "repackaging" the components and ditching the iMac display and case. Wondering if you ever followed up on this?

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@chuck077 - Sadly the display has a few sensors mixed in with the video and power feeds which input into SMC. So if you disconnect the display SMC will go into CPU Safe mode which ramps up the fans and lowers the CPU's clocking to make sure you don't burn-up your CPU!

Time to find a replacement display assembly to fix your system. 2010 21.5" iMac display assembly, Apple P/N 661-5799.

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Reading through the above comments confirms what you are saying, unfortunately. The iMac is actually a mid-2015 A1419. Apple quoted $750 for a replacement. I'm looking at other sites but not sure their quality. Any suggestions appreciated.

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@chuck077 - Sorry, was distracted here's the info for your 2015 system:

21.5" iMac Display Assembly - Non-Retina, Apple P/N 661-02989

21.5" iMac Display Assembly - Retina 4K, Apple P/N 661-02990

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I was able to get a 2014 A1419 27' imac to run outside of it's case using a TV as an external monitor. I removed the power receptacle, the power supply, cpu fan w/duct and the motherboard from the case and got it running on the bench using a mini display port to HDMI adapter. It worked well enough to get through internet recovery to install a new OS on a 1TB SSD.

CPU fan seems to be running all out. Working on that next.

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for running the A1418 iMac 2012 just cover the lower 13 pins (Pin 17 to 30) with tape on the on the LVDS connector coming from the display and connect the broken display. now the SMC can read its sensors and only the external display wil be detected because all displayport signals are on the lower 13 pins. cpu runs at full speed and fans running at normal speed.

pin 1 of the logicboard LVDS connector is on the top and has a little arrow pointing to it.

Block Image

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I have a 2014 Imac 27 5K with broken screen that the fan runs full speed if the LVDS is disconnected. Your tape solution is brilliant !..............If I new which pins to tape on my 2014 I'd be in business.

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same situation here:

my iMac 21” 2007 started to shows bad lines on video, getting worsen untill all screen was unreadable; I configured an external monitor as mirror, permanently attached via mini Display Port > HDMI.

Works well, even now that the boot from internal HD is failing one time over three.

So I decided to clone OSX 10.11 (El Capitan) onto a 128GB microSD card, plugged via USB reader, making it primary boot disk, and guess? Works even faster!!!

I suggest to try this , when you have no other options, to continue using this cool Mac.

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I have the same mac as you, although the 2007 20" version. The screen failed on me (just a bright white light) a few years back, and then the hard drive went. I somehow managed to install OSX on an external drive by disconnecting the LVDS cable inside, to force it onto an external monitor via mini-display port > vga.

Now, a few years later, that external HDD has now broken, so I'm wanting to install snow leopard again on a USB stick. However, whenever I insert the DVD and try to boot, I only get extended desktop on the external monitor. I spend minutes trying to drag the installer window over to the external monitor with no luck. Anyone know if there is a keybind to move it to the second screen, or if I can force it to boot on the external screen as main? I've tried CMD + F1, but it doesn't seem to do anything. Any ideas?

If I remove the LVDS cable, I can't even get it to boot from disc.

Driving me insane lol.

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For anyone finding this later. I just ended up installing windows 10 on a hard drive via my Windows PC, and then once it was all up and running, placed that hard drive into the Imac 2007. After booting, it realises that in the internal screen is broken, as uses the external as primary automatically. The system now works perfect (even automatically downloaded wifi drivers lol).

Anyone in the same (very niche I know...) situation, at least you have windows as a fall back.

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@SheepheadCG sorry to be late in answering; I faced the same issue but, instead of installing Windows I used Linux (elementaryOS), and I followed then the same steps you did. Eventually, if you have another mac, you can create a clone disc already setup to mirror the display.

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yes, I can confirm: mirrored display setting works as per your needs.

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Colin zal eeuwig dankbaar zijn.
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