Yosemite Update: Secondary Monitor Display With Limited Resolution Choices
2015 MacBook Air
2012 MacBook Pro 15″
NewerTech Mini DisplayPort to VGA Adapter
Optoma TW610 ST projector (connected via VGA)
With the Yosemite update, the secondary monitor display options are limited to only 2 resolutions:
1280×1024 and 800×600.
There are no other options available under the “Scaled” option.
After blaming the Thunderbolt to VGA adapter, the cable, the projector, the user (me),
the host software (in this case ProPresenter 5), hardware (a 2015 MacBook Air), it came down to an OS problem with Yosemite.
It seems Yosemite is no longer able to auto sense what’s connected through the Thunderbolt port when it comes to VGA and it does not allow you to choose from a list of possibilities.
As a side note, I did try a Thunderbolt to HDMI adaptor that worked correctly
(i.e. showing me all available resolutions).
However, there wasn’t a 50′ HDMI cable available.
How do I know it’s not a hardware (2015 MacBook Air) issue?
Because an older MacBook Pro (Mid 2012) with a fresh install of Yosemite had the same issue
and the only thing in common was Yosemite.
Needless to say, this has driven me nuts for 2 weeks.
After more research, the solution is to hold down the “option/alt key”
when selecting “Scaled” in the monitor preference.
Now all available resolutions including the one I need (1280×768) are shown.
there are different refresh rates selected between the above images; refresh rates had nothing to do with what resolutions were available;
just wanted to make a note
So, thanks Yosemite for all the stress and aggravation for the last 2 weeks.
This seems to have been an issue with Mavericks as well.
Why did it take 2 weeks to figure this out? because I only have access to the system for a few hours on Sunday mornings
and have limited time to research during the week due to the fact that I’m simply a volunteer tech
and have a day job and evening responsibilities.