Macbook External Display no Signal

Solution 1:

Here are some troubleshooting steps that I would try:

Reset the System

Reset your Mac's parameter RAM and SMC

Try another Cable

Although you are using the official MiniDVI to VGA adapter, it is possible that it might be damaged, so I would try connecting your monitor with another official adapter.

Reset the Resolution

1. Start up in Safe Mode (Power + Shift on startup)
2. Apple Menu => System Preferences
3. Choose Displays from the Views menu.
4. Select another resolution and refresh rate.
5. Restart.

Software Update

It is also possible that you need to update to Lion (Maybe even Mountain Lion if you want).

Other Links and Resources

Another Apple user who was using a Powerbook with the Acer x163W had issues too. That question was answered here and recommends a different monitor because of the Acer monitor's lower resolution than his Mac.

Solution 2:

 -> System Preferences -> Display

Press Option -> "Detect Displays" on bottom right corner

If fails, try to tick "show mirroring options in the menu bar when available"
On AirPlay menu bar, try different option and see if second display responds.