Windows – Laptop extended monitor second desktop only not working

Many people seem to have an issue with linking laptops with Mini DisplayPort output to projectors with VGA input.

Here's the real solution to my similar problem:

I purchased a Dell XPS 8700 one year ago:

• Windows 7 Home Premium
• NVIDIA(R) GeForce(R) GTX 650 Ti 1.0GB GDDR5 card

I paired it with a Dell 1610HD projector, using its stock 6 foot VGA to VGA cable, and an Apple Mini DisplayPort to VGA adaptor from Best Buy. I had no problems for a year, maybe twenty PowerPoint presentations. Then, the projector failed to detect a signal from the laptop.

I tried all the usual techniques on the laptop:

• cycling through the displays with the F1 key
• rebooting etc.

After reading online posts, I believed that my adaptor was broken, so I purchased a Rocketfish brand. Didn't work. So, I purchased the Dell brand. Didn't work.

What, I wondered, were the chances that three different manufacturer's products were defective? Not very high. I reasoned it much more likely that the problem was with the Mini DisplayPort module, itself. Most likely, the more it is used, the "looser" it becomes, making the connection with the adapters more tenuous. So, I did an experiment.

SOLUTION:

In sequence":

• I turned on the laptop
• I then turned on the projector
• I connected the VGA cable to the projector, and the adaptor to the cable.
• I used the F1 key on the laptop to toggle through the display choices to the "Duplicate" mode.
• The display on the laptop then shrinks horizontally, and says that this is isn't the optimum display resolution. I ignored that. This also works with the "Extended" mode, and the warning about resolution isn't displayed.
• I plugged the adaptor into the laptop, firmly, wiggled it around a bit to secure the connection, and waited to see if the laptop screen was displayed on the projector.
• I did this ten times for each of my three brands of adaptor, unplugging the adaptor, then plugging it back in, to calculate the success rate of each adaptor.

Results: - the Apple brand, the one which I had thought was broken, connected 90% of the time - the Rocketfish brand, 80% of the attempts - the Dell brand was successful 90% of the time.

The conclusion is that the adaptors don't break. There is no magic adaptor brand any better than any other brand. The connection between the adaptor and the laptop via the Mini DisplayPort is the culprit. The more the Mini Displayport is used, the greater the chance that it somehow works loose and suffers a failure. The key is in seating the adaptor deeply and surely, and even at that, there is an occasional failure to connect, whatever the brand. If it doesn't work once, remove the adaptor and firmly reseat it. Caution! This is very important! On my Dell, the display choice obtained by using the F1 key will always default back to "Disconnect Projector" when the adaptor is unplugged. If you don't use the F1 key each time you unplug the adaptor to reset it, the projector won't see the laptop. Always, always, use the F1 key to reset the display mode to "Duplicate" or "Extended" if you unplug and reseat the adaptor.

This occasional failure of the connection on my Dell XPS is likely the cause of failure on other laptop to projector combinations. I suspect that all Mini Displayport modules are manufactured by a single company and installed on different laptop brands, so all are subject to the inherent weakness of its design. Let's face it: the Mini Displayport isn't as robust as a VNG output found on some laptops.

I have to chalk the failure of these connections up to the inherent design of the Mini Displayport module on the laptop, and to operator error. If you don't make a secure connection, it won't work. If you still believe that the brand of the adaptor makes a difference, here are my observations on the three brands, and some measurements I took to objectify my impressions. Overall, the Dell brand (Model # DAYBNBC084) is the most robust, sturdy and well-manufactured of the three. I plan to keep it, and return one of the others, keeping the third for a spare in case I lose the Dell adaptor before an important PowerPoint presentation. The Dell is black, 8 1/2 inches long, and weighs 40.8 grams on my balance beam scale. The Rocketfish is white, 7 3/8 inches long, and weighs 33 grams. The Apple is white, 5 1/4 inches long, and weighs 32 grams. The greater weight of the Dell is chiefly due not to its greater length, but stronger construction: the wire is thicker, the convertor box is larger, and everything feels more robust. It's my choice, but as the experiment shows, all adaptors have an occasional failure rate, and the fault lies not in the adaptor, but in the Mini Displayport.

I think everything is fine on your laptop, the problem lies in the adapter or monitor.

HDMI uses pure digital signal, while VGA is pure analog. Adapter has to actively convert signal for this to work. It means there's some piece of electronics inside, and electronics sometimes just fail.

It is also possible that your monitor's backlight is dead. More on that later.

First thing to try is to connect another monitor through the same adapter. If it won't work, then you should try it without the adapter. If everything will be back to normal, then it's the adapter. You have at least two cheaper alternatives to buying a new adapter: use VGA-VGA cable or HDMI-DVI adapter. (DVI can carry digital signal and is compatible with HDMI, so you can use passive adapters here)

If another monitor will work through the same adapter or the same monitor won't work with another PC, then it's obviously monitor's fault. But there's a change you won't have to replace it. Take a flashlight and point it at the screen. If you'll see anything, then you can try replacing just the backlight inverter. (those fail sometimes)