Using a Mac computer with an external monitor or even several is essential for many. Either to increase productivity by having several screens or simply to obtain a better vision in a larger size and / or with better quality. That is why encountering problems and errors when connecting the Mac with the external screen is a real nuisance, but we are going to explain how to solve them.
Most common failures with monitors
The first thing to note is that the solutions that we are going to propose are suitable for any range of Mac , be it iMac, Mac mini, Mac Pro or any of the existing MacBooks. And it is that all of them can be connected to external monitors and therefore can also have failures, finding identical solutions for all of them.
That said and getting into the most frequent problems, we find these following, which are also solved with everything that we will expose later.
- Sudden cuts in the image , making it look good at times and at other times it goes black.
- Interference in the image , with colored stripes partially or totally present.
- Green bars that, as in the previous case, can appear on the entire screen or in only a part, either permanently or intermittently.
- The screen is completely black and does not show any image.
- Intermittent flashes. (Attention to this, because it can be very dangerous for people prone to epileptic seizures).
- It looks good, but offers the same teaching as the Mac without actually serving as a second screen on which to have other content.
Pre-checks you must do
Before you start investigating larger problems, there are some basic tips to keep in mind for the vast majority of Mac failures, including problems connecting to external monitors.
- Check the software version of your computer, as it is recommended that it always be on the latest version of macOS available to ensure proper operation. If you go to System Preferences> Software update, you can find, if there is one, the new version ready for download and installation (if your version of macOS does not have that settings panel, go to the App Store> Updates).
- Check the connection to the current , both of the Mac in case it is a desktop, and of the external panel itself. In the end it is something fundamental that, due to a mistake, we can forget and be the origin of everything. It is also convenient that if you use a MacBook, although it is not mandatory, you keep it connected to the charger.
- Restart the Mac to eliminate all those problems generated by the open processes, although it is recommended that you directly turn it off and turn it on again after a few minutes.
- Remove and replace the cable that connects the computer to the external display. It sounds stupid, but many times the connection is not detected the first time and trying again may be the simplest and most effective solution to solving the problem.
Compatibility of your Mac with other displays
Although all Macs have been compatible with monitors for several years, it is not always clear how many displays it can support and what is the way to connect them. For this reason, it is important to know the specifications of the Mac and how to configure this connection.
How to know how many it is compatible with
If you have doubts about the compatibility of your equipment with these external elements, you have a very simple way to check it. You just have to follow these steps:
- Open the Apple menu (top left of the menu bar).
- Go to About this Mac.
- Go to the ‘General’ tab and take note of the Mac model you have.
- Without leaving this panel, go now to the ‘Support’ tab.
- Click on ‘Details’.
- When the Apple website opens, click on Technical Specifications (under Resources).
- Locate your Mac model and click on it.
- In the section ‘Video support’ (or ‘Graphics’) you will put the compatibility of the computer with monitors.
Logically, you must take into account the limitations of the device. If, for example, it supports a maximum of one monitor in 4K and you are connecting two, you will have already detected the problem and therefore you can take it into account when using other screens.
View the configuration panel
If your Mac is compatible with the display (s) you have connected, you may not have configured them properly. Within System Preferences there is a section called Screens in which you can precisely review all the settings related to it.
In this panel, which is like the one you see in the previous image, you will be able to configure different aspects such as the resolution of the image that appears on the screen of the Mac itself and the monitor, the color profile, which side you want the screen to be on external, if you want the content of both to be duplicated … In short, it will allow you to manage everything related to the connection as long as it has been established well.
Possible damage to monitor, cables and adapters
With incompatibility ruled out, the chances that it is the hardware that is failing are getting higher and higher. Of course, before you go to technical support or start looking for new monitors to buy, keep in mind that they could also have an easy solution, at your fingertips and free of charge.
Cable and adapter review
The key element of connection between the Mac and the monitor is the cable and, therefore, a slight problem with this can trigger that you cannot see anything on the screen or be choppy. The first thing you should do is a visual check with which to check that the cable is in good condition, that there are no breaks in it and that it is not in a very tight position, as it could be the cause of the problems.
Keep in mind that some breaks in this element are imperceptible to the naked eye. For example, you can try to bend the cable at some points and if you notice that when doing so the connection to the monitor returns, it is because internally there is a cut cable and that it does not have a good connection.
Regarding the adapter, you should know that it is always advisable to use the native ports of the Mac. Although it is evident that it is not always possible, either because it does not have adequate ports or because they are already in use for other accessories. Therefore, the hub or adapter you use must be of good quality and fully compatible with both the monitor and the Mac itself (you will have that information in its own user guide).
Of course, you should also check that this intermediary between the cable and the Mac is in good condition. As well as it is advisable that you disconnect and reconnect as we indicated at the beginning of this post. And it is that the good connection of this element with the computer and with the monitor is essential, because if it is not fitted correctly in the port, it can cause problems like the ones you are experiencing.
If you have not just found out if these are damaged , it is advisable that you try another cable and / or adapter. This way you can make sure if it was those elements that were failing or, if there are still problems, it could be due to another cause. If you do not have any more, it is advisable that you buy another that gives you the option of returning it, since otherwise it would be a useless expense in case it is not the problem element.
Check Mac ports and monitor
You will have already checked the cables and adapters, but these can be fully compatible, of the highest quality and yet not get a good user experience. And what could it be due to? Well, as the title of this section advanced, the ports of the Mac and the external screen are damaged.
If they have several ports in which you can connect the connection cable, it is advisable that you try another to verify if it is the one you are currently using that is causing problems. You can also try connecting other types of accessories in case you are using a Thunderbolt port. See for example a memory stick, a headset with a USB-C end, or an external storage disk.
Regarding the monitor, it is more complicated to have two equal connections, but you can try to connect it to another computer or tablet that supports compatibility with it and thus rule out that it is a problem with its port.
If you also have another monitor , you can check with that one that everything is fine, being also very useful to rule out faults. If you do not have any, we cannot here recommend buying another one as we did with the cables and adapters, since in the end they are much more expensive items and returns are not always accepted.
Troubleshooting other hardware issues
At this point, it is almost certain that the problem you are having is due to a fault or factory defect in one of the two devices. Maybe even with both of them, which would be too unlucky, though not entirely out of the question.
Be that as it may, it would be pertinent that you contact Apple‘s technical service first and make an in-person appointment to take your Mac and that they can examine it in search of the origin of the problem. If they finally rule out that it has faults, it will be with the technical support of the monitor manufacturer that you should contact to request a review of it.