# built-in display not working, external monitor works OK



## HRGr (Aug 30, 2016)

Hello,

With my MacBook Air (model A1370, late 2010), the built-in display does not work. However, an external monitor attached by a "Mini DisplayPort to VGA adapter" displays 100% normally.

Over a period of weeks, the built-in display went though a series of death throes: first occasionally flickering, then occasionally showing line patterns, then occasionally showing light patterns, then becoming all whitish gray all the time, and finally becoming all black all the time. The built-in display is no longer detected by the computer. The built-in display now has no back-light, and shining a flashlight through the Apple logo on the lid suggests that either (1) no video signal is reaching the built-in display, or (2) the built-in display is not displaying the video signal.

Do the above observations provide a diagnosis that the problem is --
(a) not related to software, and
(b) not related to logic board components,
but rather is either --
(c) the LVDS cable, or
(d) the built-in display itself ?

Thanks!


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## Headrush (Feb 9, 2005)

Your diagnosis sounds reasonable to me.

That the display went through a progression of different issues leads me to believe it is option d over option c.
I'd find an Apple Authorized Repair person and have them take a look.

You might be able to find a copy of the Apple Hardware Test for your model online that would do a more thorough test.
( https://github.com/upekkha/AppleHardwareTest )


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## HRGr (Aug 30, 2016)

Headrush, thanks for your reply and suggestions.

Apple-Authorized Repair people have already opined that the NVIDIA GPU is "loose" on the logicboard – and that the logicboard therefore needs to be replaced. Given that the most expensive components on the logicboard (GPU, upgraded CPU and upgraded RAM) are all soldered in place and are thus not swappable, a new logicboard is not (I think) an economic solution for a computer from 2010. However, the external monitor displays 100% normally, so I am not yet convinced that the diagnosis of the Apple-Authorized Repair people is correct.

The Apple Hardware Test was run, in both its quick version and its extended version, before the built-in display failed completely. Both times, the AHT reported "No trouble found." However, at that time the problem with the built-in display was intermittent, so the AHT might only have reported that there was "no trouble" at that particular moment. Now, I can no longer run the AHT – because the built-in display has completely failed and it appears that the AHT is unable to display on an external monitor.


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## Headrush (Feb 9, 2005)

If AHT can't run with it failing, doesn't really help.
Authorized Apple repair normally bases their decisions a lot on that tool. 
(Disagreed with one once and cost me extra $200 for part that didn't need replacing, and what I suspected was ultimately correct.)

Prices online for Apple logic boards are generally expensive from "commercial" sites. 
Sometimes you can get lucky on eBay or Amazon. I replaced a 2011 iMac logic board for $150.
Of course yours would be more expensive because of the soldered on GPU, CPU and RAM, but you never know.

If you get to the point where you are done with the laptop and an external you could always trying re-flowing the logic board. There are many videos and discussions about it on the Internet.
I have never done that myself so I can't speak to the success rate.


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## HRGr (Aug 30, 2016)

Headrush, thanks for your reply and suggestions. I hope you have patience for more questions!

Regarding the time when you "disagreed" with an AHT result, I'm not sure that I understand. Was that AHT result later proven to have been correct -- even though you had disagreed with it? In other words, is it wise simply to accept an AHT result without questioning it? If so, then what should I make of the AHT result for my MacBook Air? The AHT twice reported "No trouble found" when in fact there was "trouble." Might that be explained by the trouble then being intermittent -- so the trouble simply was not manifesting both times when the AHT was run? Or, if the logic board was not then OK, should the AHT have found that even if the problem was intermittent?

I had not heard of "re-flowing." What an amazing idea! Over the time when the MacBook Air display problem was developing, it was running very hot (based on the felt temperature of the case bottom). Cleaning the fan and the heat pipe and doing a clean OS X reinstall fully solved that high temperature problem, but I suppose the logic board could already have been damaged during the time when the computer was running hot. At 



 there is the comment -- "his cpu or gpu is not working. these elements are getting hot so the solder is getting bad during the years. Some pins does not make connection anymore. So he puts it in the oven to melt the solder." That sounds consistent with the "loose" diagnosis made by the Authorized Apple repair people.

As mentioned earlier, an external monitor attached by a "Mini DisplayPort to VGA adapter" displays 100% normally. Is that conclusive that the logic board is OK? Or, is the video signal path to the built-in display different enough from the video signal path to an external monitor that a normal display on the external monitor is not conclusive that the logic board is OK?

Headrush, I much appreciate your thoughts on these issues.


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## Headrush (Feb 9, 2005)

Sorry for the confusion, I disagreed with the Apple Repair technician.

I had a very similar problem with an iMac. From from the beginning, I would see random screen issues on a few rare occasions. Over time it started occurring more and eventually I lost the screen completely. Using an external monitor worked perfectly. Through some trial and error, I was able to isolate loading a specific AMD video driver. If I removed that driver, the iMac screen worked in low res mode without acceleration just fine. Apple had a recall on my iMac video card, and of course at the repair shop, it passed the test fine. AHT passed fine also, but repair shop said it had to be LED driver board. Replaced that board at my cost and worked for a few days and than problems returned.

I insisted it had to be video card and he said we could try the test again, failed this time and video card was replaced by Apple. Of course, replaced with the same faulty AMD chips, and a year or so later same problem. At that point, I downgraded the video card to a working model and been working fine since.

I'm not sure why it works when an external monitor is used, as it is still using the video chip, but there must be a difference that makes enough of a difference to matter.


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## HRGr (Aug 30, 2016)

Headrush, thanks for your reply.

That was certainly a difficult and prolonged diagnosis for your computer's problem. It's puzzling why your replaced LED driver board <worked> for a few days -- and then problems returned. It's also puzzling why your replaced video card <worked> for a year or so -- and then had the same problem. One might think that replaced hardware would produce a "fixed" or "not fixed" outcome, but evidently it's not that simple. It's a good thing that you departed from Apple's advice -- or you might have had to abandon your iMac!

When my MacBook Air's built-in display had completely failed, then, using an external monitor, I made a clean install of OS X El Capitan 10.11.6 via Apple's online OS X Utilities. As of the initial boot into OS X 10.11.6, the "completely failed" built-in display worked 100% normally for 14 hours straight -- after which it abruptly failed completely again. How should I understand that? Because of that experience, I cannot yet even rule out <software> as the cause of the problem -- as how is making a clean install of OS X anything other than a change in <software>?

The temporary "fix" that apparently resulted from a clean install of OS X makes me wonder if the built-in display would work OK with an older version of OS X; i.e., a version containing an older driver for the NVIDIA GPU. To test that possibility, I should try a clean install using the Software Reinstall Drive that came with the computer in 2010. That would revert the computer to OS X Snow Leopard 10.6.

Yes, an external monitor that works 100% normally is only suggestive as to the cause of the problem -- not conclusive. As you wrote, there must be a difference in the video signal path -- a difference that is enough to matter.

Another observation that <might> be relevant to my MacBook Air's problem is that a search on the Internet shows that replacement of MacBook Air built-in display panels is quite an "industry." Of course it's not conclusive, but the fact that <many> MacBook Air built-in display panels are being sold globally suggests that the built-in display panel is, at least statistically, a likely cause of the problem with my MacBook Air.

Headrush, both your experience and mine demonstrate that results reported by the Apple Hardware Test can be wrong. That is worth knowing.


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## Headrush (Feb 9, 2005)

I don't know if I'd say the results of AHT are wrong, but more they don't always find the issue and/or it only can check a fixed number of issues.

I'd be incredibly surprised if your issue was software. Unfortunately with GPU issues, it appears the issues can be random and not always predictable. If you had a clean install on a small USB key, and you could boot off this USB stick every time the screen failed, and it worked every time, than I might inclined to think it was software related. 

Determining whether your issue is GPU or Display isn't easy for this model.
Have you made sure the one vent it has in the hinge area is clean?

Maybe try using a fan control program like smcFanControl or iStat Menus to turn your fans to maximum and see if you can get it to run longer. (I like iStat menus because I can see all kinds of hardware specifics of my machine: temperatures, fan speeds, amperages of specific components)


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## HRGr (Aug 30, 2016)

Headrush, thanks for the better statement of how to understand AHT results.

That's a great suggestion to have a clean install ready on USB. Do you mean as a bootable installer? I have made a bootable installer for OS X 10.11.6. I would also like to try that with older versions of OS X: 10.10, 10.9, 10.8 and 10.7. (OS X version 10.6 is on the OEM Software Reinstall Drive.) Can one still download earlier versions of OS X to make bootable installers for them? When I last checked the App Store, only version 10.11.6 was available for download.

Yes, all elements of the MacBook Air's cooling system are as clean as new. There is also new, high-quality thermal paste on the heatsinks for the CPU and GPU. In addition to that, whenever I have run the computer for tests, it has been mounted on a laptop cooler. From what I have seen via smcFanControl, the CPU temperature normally hovers around 40°C and peaks at about 53°C. smcFanControl is configured as you suggest.

I have never used iStat Menus. Version 5.2 looks great!

As you wrote, determining whether my MacBook Air's issue is the GPU or the built-in display isn't easy. If I cannot find a way to narrow the diagnosis, then I might just install new replacements for the built-in display and the LVDS cable. As "try-and-see" parts replacements, they would be a much less expensive place to start than the logic board.


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## Headrush (Feb 9, 2005)

No I don't mean as a bootable installer, but an actual full install of OS X that runs from the USB stick.
If a clean install always seems to fix it, when problems occur, reboot using this "pristine/clean" OS X and see if the problem really does go away or it was just coincidence. 

Sounds like you've got the possibility of over heating eliminated. This doesn't mean however that the GPU isn't faulty though.

I don't know the specifics about that model and what can be interchanged with another part, but if you knew someone with the same model so you could use for example, their display to narrow the issue is the only way I think. 

If you're going to try and replace parts, I would suggest sticking to as reputable as you can suppliers.
I replaced a LVDS cable on a 24" iMac before and the first one I got was faulty. After finally figuring that out, I bought a second one that did work, but it was different than the original, although it was stated as exact same.
(It was slightly shorter and cable was round rather than flat which made installing incredibly difficult.


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## HRGr (Aug 30, 2016)

Headrush, thanks for clarifying that it's an actual full install of OS X that runs from a USB stick. Can you point me to instructions for how to make that?

Yes, eliminating the overheating doesn't rule out the GPU being faulty.

It would indeed be highly diagnostic to do the parts interchange that you suggest. I don't know of another MacBook Air from late 2010 (model A1370, configuration MC506LL/A), but no doubt some of that model and configuration are still "out there" and working normally.

Regarding reputable suppliers, an LVDS cable is advertised on eBay as "Apple" and "new," and its photo looks right -- but your LVDS cable buying experiences certainly make for a cautionary tale!

In the absence of a diagnostic breakthrough, my thoughts for proceeding further are to minimize effort, risk and cost by following this sequence:
(1) try again to get the Apple Hardware Test to display on an external monitor -- and if that succeeds, re-run its extended version;
(2) try running a full "clean install" of OS X 10.11.6 from a USB stick;
(3) try installing OS X 10.6 from the computer's Software Reinstall Drive;
(4) check all connections (e.g., ribbon cables in ZIF sockets);
(5) wiggle-test the LVDS cable (it may be possible to wiggle that cable with the computer running and the bottom case housing removed);
(6) continuity-test the LVDS cable (that's where "effort" really starts, as it would require removing the glued-on bezel);
(7) replace the LVDS cable;
(8) replace the 11.6-inch built-in display (just the LCD screen -- not the back cover, bezel, LED back light, diffusers or iSight camera);
(9) re-flow the logic board (that's where "risk" really starts);
(10) replace the logic board (that's where "cost" really starts).


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## Headrush (Feb 9, 2005)

There are no different steps for installing on a USB stick. Just point the installer to install on the stick (needs 8GB+)

The steps you outlined seemed reasonable to me.

I would pause at step 7 and evaluate the cost vs reward. I haven't looked at the going rates, but usually pieces like LCD display or logic boards are expensive (For Macs).
Is it really worth the price for a 2010 model that will likely be unsupported soon. Checking the Apple Refurb store might be better for long term use. You can get a new or next to new machine, save a few hundred dollars and have a machine that is supported and still has the full Apple warranty. You probably can still sell yours as the rest is working and recover some of the cost there also.


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## HRGr (Aug 30, 2016)

Headrush, thanks for your reply.

I now understand how to install OS X on a USB stick, thanks.

Both the LVDS cable and the LCD panel are inexpensive. However, the logic board <is> expensive -- too expensive (I think) to justify for a Mac from 2010. I appreciate your suggestions about the Apple Refurb store and about selling my Mac.

Headrush, thanks again for all your help with this.


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## Headrush (Feb 9, 2005)

Take your time and best of luck.

Sounds like one of the harder fixes to do: https://www.ifixit.com/Answers/View...just+the+LCD+screen+for+the+A1369+MacBook+Air

How much are you seeing displays for? I'm seeing around $200. I'm also seeing entire working MBAs for $350 in my area.


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## HRGr (Aug 30, 2016)

Headrush, thanks for your reply.

For replacing the LCD panel, I understand that "glue" is the main obstacle. While some articles emphasize difficulty, excellent how-to videos on YouTube are more encouraging.

In my area, the best price I've seen for the full display assembly is €175 -- about the same as what you've seen. However, for entire working MBAs the prices in my area are at least twice what you've seen. Was the $350 price perhaps a private sale (i.e., not from a commercial seller)?

Fortunately, the LVDS cable costs only about €10 and the LCD panel costs only about €30. Such prices help to justify an attempt to "save" an older MBA.


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