Announcement: Upgrade to macOS Mojave

With features like Dark Mode, Stacks, and four new built-in apps, macOS Mojave helps you get more out of every click. 
Find out how to upgrade to macOS Mojave > https://support.apple.com/macos/mojave

Looks like no one’s replied in a while. To start the conversation again, simply ask a new question.

Question:

Question: 3 monitors question - 2 iMacs + Pc monitor

What do I do to have 3 monitors display all at the same time?

I can get my 27" iMac (High Sierra) to my 21" iMaC -10.11.6 El Capitan to display ok actually with no problem.

But when I use my pc monitor (which is plugged in to the back of my 21" IMac ), It does't show up in preferences

of my Main 27" iMac. Nor does it show up in 21" iMac. I know this because in Prefrences - "Displays" in the "Arrangement" section I don't see 3 monitors ! I should have 3 monitors show up that I can drag to the right or left etc. And then be able to change that strip of white to the various windows etc.


What am I doing wrong?


Again my two iMacs show up and work in tandem, but the pc monitor wants nothing to do the the 2 iMacs.

The PC monitor chord to hook in the back of my iMac is into the 21" iMac to PC VGA! ! But it doesn't work in the 27"iMac to VGA-PC either.


Sorry If I am repeating myself !

Bill

iMac with Retina 5K display, macOS High Sierra (10.13.1), + El-Capitan Imac 21"/ Pc monitor

Posted on

Reply

Page content loaded

Nov 11, 2017 12:33 PM in response to Luis Sequeira1 In response to Luis Sequeira1

Thanks Luis for getting back to me so soon!


The first "mini-display port (thunderbolt) is plugged into my iMac 12" from my iMac 17" Retina Display

5K, 2015 ! Using the thunderbolt cord (on each side) The second thunderbolt port in back of my 27" iMac is

hooked up to a VGA on one end (into the 21" iMac) to the thunderbolt of the 27" iMac .


I was on the phone with Applexcare support, and I thought I actually had got the problem fixed. But then I started to change the monitors (position wise) and then I lost the concept of what I was supposed to do. I remembered the thing that finally got me the 3 displays in the "Arrangement" window and that was to put the head Imac to sleep for a few seconds ! And was really happy that I thought I finally fix the problem with the help of the AppleCare lady. But being that I changed the monitor location, I can't repeat the success I had. I want my 27" iMac to be on the far right, then to the left of that I want the 21" iMac, the to the left of that I want my PC Monitor! it is the PC monitor that has the VGA hookup into it, and then into my second Mini Display port (thunderbolt) of the iMac 27" is a "Rocketfish adapter that is a VGA to Thunderbolt connect adapter into the 2nd port of 27" iMac!


Thanks again Luis for getting back to me so soon!

Nov 11, 2017 12:33 PM

Reply Helpful

Nov 12, 2017 4:35 AM in response to Acguitarmac In response to Acguitarmac

Acguitarmac wrote:


Thanks Luis for getting back to me so soon!


The first "mini-display port (thunderbolt) is plugged into my iMac 12" from my iMac 17" Retina Display

5K, 2015 ! Using the thunderbolt cord (on each side) The second thunderbolt port in back of my 27" iMac is

hooked up to a VGA on one end (into the 21" iMac) to the thunderbolt of the 27" iMac .


This last part does not make sense.

What you should do is attach the miniDisplayPort-VGA adapter to your 27" imac, and connect the external display to it, NOT to the 21".

Nov 12, 2017 4:35 AM

Reply Helpful

Nov 12, 2017 6:25 AM in response to Luis Sequeira1 In response to Luis Sequeira1

Good point, I used the VGA adapter to be adapted to my 27" iMac -VGA to Thunderbolt.

Coming out of the PC monitor.


First problem fixed, got the 3 monitors accomplished!

I really do appreciate you Luis for responding!


I finally fixed the problem with the help of an tech support guy from AppleCare .

When I finally lined up the two iMacs and the PC monitors. What I didn't do was to press the Command key and the F2 key together on my second IMac monitor which is the "Target" monitor which is the slave to the main 27" monitor.

Then and only then did I see the 3 arrangement windows show up form the Preferences - Display section Where there was two, now there was finally 3. So I have to keep remembering that precious "Command +F2" key! in the "Target "iMac 21!


2nd problem not fixed:

Now that I have 3 monitors up and running (as long as I don't forget the process)

I have now my two thunderbolt ports filled up in my Master iMac 27" because of

the need to use them for the 3 monitors (Two iMacs +Pc monitor)

So being that I use Logic Pro X for composing, i use a UAD Audio Interface Thunderbolt!

That interface gives me high quality sound. But I have NO port in which to plug it into.

The Thunderbolt ports or "Mini Display Ports" are filled up. I went to Best Buy because Apple

store couldn't find what I was looking for, Best Buy could't find it either, a male (Thunderbolt to USB adapter)

so I could plug the Thunderbolt audio interface into one of the 4 ports in the back of my 27" iMac !


++++++++++++++++++++++++ 😟

So I am at a brick wall. To my knowledge there is not a "Thunderbolt to USB adapter made". And not sure it would work either ! Because I want to have 3 monitors for all the windows I open up working in Logic Pro x.

I paid a decent amount of money for that Thunderbolt UAD audio interface and I just don't want to go out and by another. So many I'm stuck with two monitors working with Logic Pro X.

+++++++++++++++++++++++

So I will send Universal Audio message asking them if there is a work around. I am not sure if they are discontinuing

the Thunderbolt model ! They do have a USB version which would be good but I just don't want to keep dishing out money buying audio interfaces!

Thanks again Luis for getting back to me !

Nov 12, 2017 6:25 AM

Reply Helpful

Nov 12, 2017 10:31 AM in response to Acguitarmac In response to Acguitarmac

There is no such thing as a USB3 to Thunderbolt converter. The other way around is possible, but obviously


Among your options:


1) Live with two monitors (I know you like three, but you already have an immense screen real estate on the 27" alone... )


2) Find a USB3 display adapter with mac drivers and connect your pc monitor to that, thus freeing one Thunderbolt port.


3) Use a Thunderbolt dock which allows you to connect the pc monitor and daisy chain the Thunderbolt device off of it. I know there are several such Docks with HDMI connections, but I don't think there is one with VGA. I don't know if an HDMI->VGA adapter connected to one such dock would work.


Or you could live happily with option 1...

Nov 12, 2017 10:31 AM

Reply Helpful
User profile for user: Acguitarmac

Question: 3 monitors question - 2 iMacs + Pc monitor