Mini Thunderbolt to VGA not showing video on external monitor but Mac says it is The external monitor used to be working before, but now, there's no video being sent. The monitor is sleeping when I connect, even though the mac says it's connected.

I am using a SyncMaster390b as the monitor.

I tried turning it on and off and reconnecting everything, but still no luck.

Any help?
The problem that you are facing is simple to fix. Actually there is no inbuilt Thunderbolt to VGA drive inside a MacBook/Mac mini. So what you should do is install a Mini DisplayPort to VGA Firmware Update v1.0. After installation restart the system, then connect your thunderbolt to VGA connector. It will work perfectly fine.

Here is the link for the driver where you can download it:

https://support.apple.com/kb/DL799?locale=en_US