Question :

I have a Benq BL2420PT external monitor as a desktop screen connected to my MacBook using a Displayport-cable (actually a miniDisplayport-to-Displayport-cable). When my MacBook goes into sleep mode or the Ben monitor goes into sleep mode itself the screen goes black. But when I try to revive the monitor by moving my external mouse or pressing any key on my (external) keyboard, the MacBook starts up, but the Ben monitor’s screen stays black.

This same thing sometimes happens when I startup my MacBook and close the lid before the Benq monitor switches on.

What can I do to fix this ?

Answer :

The following trick might help for other Benq monitors, and maybe even for different brands of monitors also. This works for the Benq BL2420PT monitor if the screen stays black even when the connected Mac is turned on :

• on the frame of the screen, bottom right, you see 5 indicator lights, next to the Power-indicator ; these are all touch-buttons
• if the Power-indicator/button is steadily glowing in white, don’t touch it ; only if it has another color, touch it to switch on the monitor
• if the Power-indicator still doesn’t glow white, check if all cables are connected properly and make sure the physical ON/OFF-switch on the bottom of the screen is switched ON
• touch the one indicator light/button that is nearest to the centre of the screen (so the most left one)
• if a message appears “No cable connected”, just wait
• if a menu appears with 5 cable connectors to choose from, don’t touch anything, just wait
• just wait (usually up to 30 seconds, sometimes even a minute) and the screen will switch on

NOTE : the most important thing is that you DO NOT (neither accidentally nor intentionally) touch any other indicator/button ! as this usually screws up the monitor’s software setting that corresponds to the physical cable connection (to correct that, you should toggle around with the these touch-buttons until the menu with the 5 cable connectors reappears and you can then choose the one that corresponds to your physically connected cable)

If the above doesn’t work, look here for alternate procedures to revive your black screen :

fixed : MacBook’s external monitor screen stays black

That’s it !

enjoy 😉