No signal on external display

I have an aluminium unibody 13” macbook pro. It has broken display, so I am using it as desktop mac by connecting it to LG Full HD TV with HDMI connection.
Sometimes i got "no signal" message on TV but after rebooting mac or reconnecting HDMI cable, signal came back. Previously it came back only after many reboots and other experiments. It worked wih no problems for about 2 months and now I am stuck with same problem again.
Where can be reason for this problem? I can connect trough VNC and control everything. When I reboot, Apple logo comes up, but then it changes to no signal, when graphic interface has to come visible.
I will try change my HDMI cable later, when I will get one, but can it be cable problem, since I still can see bootscreen?

Hello,
I am running an imac 27" (Raedon display graphics) with the Mini Display port to VGA adapter and I get "no signal" on the ACER monitor either. Although the iMac recognizes the second monitor (I can change the display settings), I cannot get anything on the monitor(still no signal). I have tried the ACER monitor on another PC and it works fine...I do not seem to be the only one with this issue...anyone have any ideas?
Thanks in advance

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No signal to external display

I'm having trouble with connecting my Macbook Pro to my Samsung TV (via HDMI) to use as an external display. When I plug the HDMI cable into my laptop the screen flashes like it detects another display but then nothing changes and the TV still reads no signal. I've connected the laptop to a different TV and it worked just fine. I tried connecting a different laptop to the TV and that one didn't work either. I've also connected an AppleTV to my Samsung (the one I'm having issues with) using the HDMI cable that I'm trying to connect the laptop with and that worked as well. I've tried both the STB and DVI HDMI ports on the TV and neither of them work.
Any help would be greatly appreciated.
For more information:
It's a late 2013 Retina 13" Macbook Pro running OS X 10.9.4.
The TV is a Samsung UN29F4000.

Hi there Elpenor,
You may want to try the troubleshooting steps located in the following article to help you address this issue:
Apple computers: Troubleshooting issues with video on internal or external displays
http://support.apple.com/kb/HT1573
Thanks for coming to the Apple Support Communities!
Cheers,
Braden

Stop sending signal to external display without unplugging the cable

Stupid question: if I toggle through the display settings (F7), it doesn't seem as if any go to shutting off the external display (like maybe I want to make a change I don't want my audience to see, I would like to shut it off without unplugging, then turn it back on when I'm done). Did I just not toggle through enough? Or is there a different mechanism to accomplish this?
(I also looked in System Preferences --> Display, but see no command for shutting off the external display once it is connected/detected.)
Thanks!

Hi, Phlaug. There is no such setting. But if you use Extended Desktop mode instead of Display Mirroring mode, nothing that appears on your MBP's screen needs to appear on the external display (or projector) that your audience is seeing.
Instructions from Mac Help, under the Help menu:
*Setting up multiple displays as an extended desktop*
If your computer is connected to more than one display or to a TV or projector, you can set them up as a continuous display for your desktop.
To set up multiple displays as an extended desktop:
Connect the displays to your computer.
Connecting multiple displays or a projector
Open System Preferences, click Displays, and then click Arrangement.
Open the Display arrangement pane of Displays preferences
Follow the onscreen instructions.
You can also show the same image on all the displays connected to your computer. This is called “video mirroring.”
Setting up multiple displays to show the same image
If your computer is connected to more than two displays, you can specify that some are mirrored displays and others show the extended desktop. For example, if you have three displays, you can have two displays showing the same information and the third display showing the extended desktop. To set up a combination of displays showing mirrored and extended desktop images, set up the three displays as an extended desktop, and then Option-drag a display icon onto another display icon to mirror the two displays.
If you are playing a DVD on a television connected to your computer, click the Arrangement button in Displays preferences and move the menu bar to the television. If you don’t see an Arrangement button, your computer is only capable of mirroring (showing the same image on all screens). For more information, see the manual that came with your computer.

MacBook not sending signal to external display - was working fine before.

hi guys, i have a unibody macbook and i've been hooking it up to my tv for almost 2 years now using the mini display port to hdmi adapter and hdmi to my television.
tonight the macbook randomly stopped sending signals to the tv. i tried two tvs with two different display adapters as well as a DVI monitor.
the displays are detected in osx but there is just no signal sending to it. anyone have any ideas? did my mini display port just die? i've tried several cables/adapters.

Hey,
I just experienced a similar problem as the original poster, except that I'm using a minidisplayport - DVI adapter and not HDMI. Been working fine on my external screen for 2 months now and suddenly the external says no signal?
Macbook still flashes a blue screen when plugging in the adapter but does not detect the external. Haven't ruled out that the adapter is busted yet, but worked fine earlier.
I tried resetting the PRAM without any change.
Any kind of software / hardware problems on the macbook?
Any thoughts?

No signal to external Display/LCD-TV

I own a Macbook Air 13" (Late 2010) and used to connect it via Mini-Display-Port to HDMI-Cable to my LG 37" LCD TV. While on Snow Leopard everything worked fine. Now I upgraded to Lion and I am not able to get a signal to my TV. The MacBook Air lists my TV in the display settings but I cannot get a signal to my TV. I tried ever resolution and setup but it does not work. I also tried to delete the com.apple.windowserver.plist and resetting PRAM, nothing worked. Can anybody help me with this? Greetings from Germany.

Did you do anything to make it work? Mine used to work but when I tried it a different TV the adapter and TV weren't recnized by the the MacAir?

MACBOOK PRO - NO SIGNAL OUTPUT TO EXTERNAL DISPLAYS

When connecting any external monitor I have an intermittent issue where it does send the signal to the external display - yet it shows the display's preferences in the Control Panel. Had an embarrassing moment at a presentation with an LCD projector. Have used severalo DVI adaptors. Any ideas? It works sometimes, sometimes it does not. When it works I cannot close the lid either without it turning off everything, which used to work fine.
Any ideas?

It's too bad you never received any help on this in the Forums, but was hoping you may have come across a solution in the last 2 years.
I am not a techie, so my explanation will be crude, but sounds exactly like your issue above. It's October 2013...I have a 2008 MacBook Pro. Everyone tells me I can use the miniport to connect to my 2010 LG TV. I purchased a Mini DisplayPort to HDMI Adapter from RadioShack (Gigaware brand). I plugged the adaptor into my minport, plugged the HDMI cord into the adaptor, and plugged the other end of the HDMI cord into the LG TV (44"). In my display preference, the MacBook recognizes the TV. However, there is virtually no picture...
I get extreme fuzz/snow with colored pixels, with the background display flickering on every 30-45 seconds behind the fuzz (i.e. very grainy). On one occassion, the display showed up perfectly for a nanosecond and went back to fuzz. Common sense is telling me that the image is trying to be sent to the TV but the signal is not strong enough? Or, the encoding is not fast enough?
Tried the following:
Grabbed another HDMI cord in case it was the originally cord - no dice.
Tried all 4 HDMI inputs on the TV - no dice.
Myriad other non-technical things like moving the MBP around, jiggering with connections, etc. Nothing.
For purposes of meeting my needs, I ended up downloading the latest Apple TV software and ended up displaying my presentation via Airplay from my iPad. But that solution drops a lot of the key attributes of my presentation (slide builds don't work, certain graphics missing, color is off, etc). It worked sufficiently, but I was hoping for a more solid presentation solution.
Thanks for listening!

No external display signal

I recently purchased a miniDisplayPort to HDMI so I could have an external display.
I am getting no signal from my Samsung 32in TV.
Is it not possible to use this cable?
Unfortunately, I've looked around on the Internet and couldn't find anything so I had to come on here. Thanks!

Hello Jon,
Does the TV have a setting choice of inputs, like maybe PC instead of Cable.DVD, etc?

How do I get my Macbook Pro to detect an external display?

Hi there.
I just bought a new MacBook Pro today.
Everything about it is wonderful, except: When I plug an external display into the Thunderbolt port using a Minidisplay port to VGA adapter, it doesn't send a signal to the external monitor. The screen on my Macbook will go blue for a second, and then the windows freeze. The mouse will be movable for a bit (up to a minute), but nothing is clickable. Strangely, it seems as though it's functioning as if there were a second monitor (I can move the mouse off-screen as though it's going over to another display). But then the spinning rainbow wheel starts and never stops. If I unplug the Minidisplay port to VGA adapter, the Macbook will snap back into professional mode and everything works again.
If I try to boot the computer up with the Minidisplay port to VGA adapter already pluged in, it simply won't boot up (I get a gray screen with an apple and nothing more).
I tried using gfxCardStatus set to "discreet only" and I still have this problem. I tried to run a firmware update, but my comp seems to be entirely up-to-date already (just set it up today).
The monitor and adapter seem to be working fine, and function as an external display when pluged into the Mini-DVI port on my 2009 Macbook running Snow Leopard.
I guess my question is, what's causing this? Is this an adapter problem? Like, do I need a special adapter to use with a Thunderbolt port as opposed to the one I'm using which works when pluged into a Mini-DVI port?
Model Name: MacBook Pro
Model Identifier: MacBookPro9,2
Processor Name: Intel Core i7
Processor Speed: 2.9 GHz
Number of Processors: 1
Total Number of Cores: 2
L2 Cache (per Core): 256 KB
L3 Cache: 4 MB
Memory: 8 GB
Boot ROM Version: MBP91.00D3.B08

The only thing that I can suggest is trying a different adapter - such as this one from Monoprice.
I don't know if that's the root of your problem, though. Does the external monitor have DVI? You could get a Thunderbolt to DVI adapter from Monoprice - here - and give that a shot.
Clinton

MacBook Pro cannot connect to external display (projector) under Windows

Our office has got one of those lovely new 13" MacBook Pros and we cannot figure out why it cannot connect to either of our 2 projectors with Windows 7.
We have an older MBP with NVidia graphics that connects just fine under both OS X and Windows. And this machine connects fine under Snow Leopard.
There was a recent Thunderbolt chipset update and we applied that; on the Windows side the Intel driver has been updated but nothing happens. Have also zapped the PRAM to no effect.
To add another wrinkle: I just connected the MBP to my Cinema Display and the external display shows fine in both OS X and Windows--Windows didn't even require me to go to the control panel.
This leads me to two thoughts: either it is something with the Thunderbolt to VGA adaptor (hard to believe, though, since it works for OS X) or it is something to do with the native resolution of the projector (equally hard to believe, as changing through various settings in Windows NOTHING happens on the external projector--it doesn't blink, go back or anything.)
Any ideas?

I wish I could find the discussion, but I cannot.
There was a discussion about the Windows 7 driver for the Thunderbolt port. The conclusion I believe was that it only outputs digital signals, not analog.
The other conclusions were:
A USB-VGA adapter adapter bypasses this limitation because the driver is in the adapter itself and works regardless of the OSX/Windows operating system in charge.
Run Windows under VM, where OSX is in charge and can create analog output through Thunderbolt
If only I could find that thread ...

External display via Mini DisplayPort to DVI no longer works with MacBook.

I had not used my external monitor in the last several weeks. I believe there have been a few OSX Lion updates since the last time I used the external monitor. I had installed all the updates prior to connecting my external monitor again. However, a few days ago I tried to connect the external monitor and all I get is a "No Signal" message on my external monitor. The Mini DisplayPort to HDMI works on my LCD TV, so I know the MDP works. I have also replaced the MDP-to-DVI cord and the external display still doesn't work.
I connected the external monitor to another computer running Snow Leopard and the external monitor works. So, the external monitor does work.
I have seen a few posts aboout this, but nobody seems to have a solution that works or is directly on point to my issue. I have tried to use all the scenarios for plugging in the external monitor and external monitor power. I tried to reboot the laptop with and withoout the external monitor connected. Same thing with the exteernal monitor plugged in and no power, etc. Nothing works. I have tried to repeatedly turn the external monitor on and off while connected to the MacBook. Again, that doesn't work.
So, I am open to any help someone may have. Here is what I am running:
MacBook, Aluminum 13" Late 2008
OSX 10.7.3
NVIDIA GeForce 9400M

While we all have MacBooks in this forum most of us don’t run Lion. There's a Lion Support Community where everybody has Lion. You should also post this question there to increase your chances of getting an answer. Lion seems to have problems with external monitors. https://discussions.apple.com/community/mac_os/mac_os_x_v10.7_lion

Can I use External Display on a Window 7 64bit 13" Macbook Pro Early 2010

I have a 23" LED LG Monitor , It has VGA Cable , RCA Cable and HDMI Plug (but no wire). I am asking now if whether I should need a VGA Cable or a RCA Cable or a HDMI cable. I know there's the Apple Mini DVI to VGA Adapter. Should I get that? And does window 7 64bit professional bootcamp support any external display? If not , is there another way to get it working.

You should be able to hook it right up just like if it was a "normal" Windows Laptop.
Windows would be the one to set it up with. Make sure you've updated Boot Camp.
You probably should use an "Apple Mini Display" port -to- HDMI adapter as that should give you more display options, etc. (I'm not sure how high the 13" can go on resolutions, HDMI or VGA may not matter?)
You MAY have to use a separate sound cable between the laptop and monitor as some HDMI -to- (whatever) adapters don't carry the sound signal via an "adapter".
The next choice would be a Mini Display port to VGA adapter.
You may want to also ask this question in the "Computing Hardware/MacBook Pro" area as they may have more info?
Hope this helps...

External Display (Mini Displayport) doesn't work

I have a mid-2010 13" MacBook Pro. The Mini DisplayPort sends NO signal to an external display, either adapted to VGA, DVI, or HDMI.
I've tried two separate displays (neither Apple branded), one of which is brand new, and both work perfectly well with my iMac and Mac Mini . . . but, nadda with my MacBook Pro.
I brought it in to the Apple Store in Belfast last week and the Genius Bar did the normal testing on it ... where it failed when hooked-up to a basic VGA LCD screen.
... BUT ... when they connected it to an Apple branded display it worked immediately.
Well, that's SOMEWHAT good news ... however, I have no intention of buying an Apple display (uhh ... yet).
I've scoured the newsgroups and discussions for an answer, but all the answers I found didn't help me.
Yep, it WORKS when connected to an Apple display, but that's it. And, the cabling and displays I'm using work fine connected to my other Macs.
"Detect Display" (holding down the ALT key to make it appear) does nothing for me.
I've tried Safe Mode boot ... no help.
I've tried with and without mains power (to the MacBook), and the results are the same both ways.
I've tried resetting the PRAM ... no help.
The fella at the Apple Store was stumped. They are willing to examine the machine and let me know what they find, but, this is my primary working machine and I don't have the luxury of such down-time without it.
Any thoughts? Any obvious (or, not-so-obvious) tricks you can finally think of? (short of buying an Apple display)
Thanks
Allan Shearer
Ireland

I knew that, Jin Li Thanks for the pic.
The question is whether hellothere's machine has thunderbolt. If my theory is right, then switching tb off might not help, since the problem would be with one of the video components (in the TV or the computer) not recognizing the other as a trusted make/model.

How do I set MacBook to an external display when the plug and play doesn't recognize it? I am trying to set my Samsung 530 LCD as a monitor but HDMI and VGA cords (and the adaptor for them) doesn't seem to work.

I have tried everything I can find on line but they all claim that the plug and play works, and they don't for me. I tried the mini dvi to HDMI and a HDMI cord and that was not recognized no matter which unit I rebooted first. I found someone who said that my Macbook might be too old for the HDMI technology so I returned the cords and went to the VGA cord and adaptor.
I tried this first with the HDMI setup:
http://support-us.samsung.com/cyber/popup/iframe/pop_troubleshooting_fr.jsp?idx= 167919&modelname=LN40C650L1F&modelcode=&session_id=NDhJrD0DQT0Z8KRsm62yhxJxqnyPy SKhlhpB8vQ6h9Q7R2BZJGzj!-1089109758!1761676444!7501!-1!434477884!1761676348!7501 !-1!1292098185857
Then I tried this with the VGA setup:
http://support-us.samsung.com/cyber/popup/iframe/pop_troubleshooting_fr.jsp?idx= 167901&modelname=LN40C650L1F&modelcode=&session_id=NDhJrD0DQT0Z8KRsm62yhxJxqnyPy SKhlhpB8vQ6h9Q7R2BZJGzj!-1089109758!1761676444!7501!-1!434477884!1761676348!7501 !-1!1292098185857
I contacted Samsung support and they said I needed to set the display settings to external display on the mac. I went to the display settings and moved the icon to my status bar. When I click on search for displays or whatever it says (I'm not at my Mac right now) it does nothing.
What am I missing?

I am using MAC OSx 10.5.8 (9L31a) as my operation system. The TV says "No signal. Check connected device's power, cable connection and source selection." Seems to me that that goes in hand with what the Samsung tech said about the Mac needing to be forces to use the external display. But how do I do that?

Is there a way to use a non-apple external display (monitor) without having my macbook air plugged in?

Just got a 27'' AOC monitor that I'm using with my Macbook Air (purchased in 2013). It's working great but as soon as I unplug the power adapter from my laptop the monitor goes black and says 'no signal'. I've been reading online that you need to have the power adapter plugged in to use an external monitor - my questions are: 1) does that harm the laptop's batter? if so, 2) is there a workaround? if there is no workaround, 3) does an Apple monitor also require that a laptop be plugged in for the external display to continue functioning while the laptop is in clamshell mode (closed lid)?
Thanks in advance for any advice

Thanks, Matt. In my case, the monitor definitely shuts off when I unplug the power from my laptop in clamshell mode. If the lid is open, however, the monitor continues to function even without the power adapter plugged into my laptop. Ideally, I'd like to have the lid closed on my laptop and be able to use the external monitor without having the power plugged into my laptop. That's what doesn't seem to work - if your does, please let me know if you have any pointers.
Thanks again!

Intel iMac won't recognize external display with Dynex mini-DVI adapter

I've got an original Intel iMac with a Mini-DVI connection on the back. I'm attempting to hook it up to an external display (a plasma screen, in fact). I picked up a Dynex Mini DVI to Video Adapter DX-AP100 for Apple. This connector has a mini-DVI connector on one end, and both a video-out and an S-video-out on the other.
When attempting to use the adapter, the iMac does not recognize that there is an external display connected. Here are the facts:
The external display: I've tried this with a Panasonic Plasma screen connected directly through S-video, as well as a Pioneer receiver (one that switches video) connected both through s-video and composite video. And yes, I've got the settings on the TV correct. I've also tried this with a Polaroid LCD TV connected via S-video and composite video.
I did notice that when I click "Detect Displays" while the Plasma was connected, the plasma briefly "flashed", implying SOMETHING was happening, but still no dice.
Anyone have any experience with this Dynex DX-AP100 that could share some wisdom?
OS: v10.5.6
System Profiler:
ATI Radeon X1600:
Chipset Model: ATY,RadeonX1600
Type: Display
Bus: PCIe
PCIe Lane Width: x16
VRAM (Total): 128 MB
Vendor: ATI (0x1002)
Device ID: 0x71c5
Revision ID: 0x0000
EFI Driver Version: 01.00.068
Displays:
iMac:
Resolution: 1440 x 900
Depth: 32-bit Color
Core Image: Hardware Accelerated
Main Display: Yes
Mirror: Off
Online: Yes
Quartz Extreme: Supported
Built-In: Yes
Display Connector:
Status: No display connected

Yeah, I realize S-video is limiting, but I'm trying to keep things as simple as possible. The TV is mounted to the wall and there are not currently any DVI or HDMI cables coming out of it. There's an S-video input from my receiver that I'd prefer to use since it's readily accessible already. In the end my goal is to use Netflix "Watch Now" on the TV, so I'm not too worried about video quality.
and before someone asks if I considered that the receiver's S-video input might be the problem...I tried taking the s-video wire from the stereo and plugging it directly into the adapter. No dice.
ONE ADDITIONAL PIECE of information...while trying to get this to work on an LCD monitor, I plugged the composite video connection from the TV into the adapter. Suddenly the Mac recognized an additional monitor, but it saw it as a VGA monitor, not as s-video or composite video, and no signal went to the TV.
I'm considering trading in this adapter for a mini-DVI to VGA adapter, but that really won't help me with the connection to the TV.

No signal on external display

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