Can I Connect A Thunderbolt Display (A1407) to an iMac Retina 27?

[chrison600]

Hello there,

I recently purchased a refurb Thunderbolt Display. I have it connected now to my iMac Retina 27 (2015) via the Thunderbolt cable integrated into the monitor (MagSafe has nothing to connect to). It is connected to power as well.

The monitor is not turning on and not showing in the System Preferences. I've had two support chats with Apple Support today and no real assistance. I would try this monitor on my MacBook Pro, but it's the newer style with all USB-C ports and I have no USB-C to Thunderbolt-2 connectivity.

Is this even a possible combination? (iMac 27 + Thunderbolt Display)

 

[chscag]

Where did you purchase the refurbed TB display? In other words, who did the refurbishing? Apple no longer stocks these displays in their refurbished store although they are still supported for repairs.

The support notes for the monitor state that it can only be connected through the Thunderbolt Port. You should be able to connect it from one of the Thunderbolt output ports on your iMac to the Thunderbolt port on the display. Does the monitor power up at all?

 

[chscag]

Further info on this:

According to the specs, the Thunderbolt built in cable on the display is for daisy chaining another TB display and not for connecting to your iMac. Try what I suggested above by going from TB out on your iMac to TB in on the display. Do not use the built in cable.

 

[chrison600]

Try what I suggested above by going from TB out on your iMac to TB in on the display. Do not use the built in cable.

Thank you chscag. I suspected this, so I have an Apple official Thunderbolt cable en route, due tomorrow. I'll try that and cross my fingers.

 

[MacInWin]

Further info on this:

According to the specs, the Thunderbolt built in cable on the display is for daisy chaining another TB display and not for connecting to your iMac. Try what I suggested above by going from TB out on your iMac to TB in on the display. Do not use the built in cable.

I have a TB display and the built in cable connects to my MBP just fine through the TB port. It has a power connector to power the MBP as well, so clearly Apple intended the cable to be attached to the MBP.

 

[chscag]

It has a power connector to power the MBP as well, so clearly Apple intended the cable to be attached to the MBP.

But not to an iMac? My understanding is that the A1407 can be daisy chained to another TB display by using the built in TB cable. Is that not true? Or by using a TB cable from one TB display to the TB input on another TB display?

So... does that built in TB cable provide video output or is it used for video input?

 

[chscag]

Just reading up on his iMac.... He has to use a Thunderbolt 2 cable to the Thunderbolt input on the monitor in order for it to work. That according to Mactracker.

 

[chrison600]

Sounds like I'm going to be a guinea pig here...

I have the 2015 iMac 27 and a MacBook Pro, but the MacBook is the newer chassis with the 4x USB-C ports.

 

[chscag]

Your 2015 iMac has the same outputs as mine except my model has TB 3 output ports and yours uses TB 2. According to Mactracker, you should be able to go from one of your TB 2 ports to the TB input port on the display and it will work.

Your MacBook Pro will likely need a USB-C to TB adapter in order to work the same way. I have no idea if the TB display will work with your MacBook Pro the same way that Jake's (member MacInWin) does.

 

[chrison600]

Your MacBook Pro will likely need a USB-C to TB adapter in order to work the same way. I have no idea if the TB display will work with your MacBook Pro the same way that Jake's (member MacInWin) does.

I'm not interested in using the Thunderbolt display with the MBP. I use that when I'm mobile. The Thunderbolt display is a replacement for a BenQ GW2765 I've used for a few years. It didn't really need replacing, and it's been fine, but the Thunderbolts came up on Woot and I grabbed one, so I hope it works ok...

 

[MacInWin]

What I have set up is the TB display cable is attached to the TB port and to the power outlet on the MBP. I do have to use a little adapter for the MagSafe connection, but it just changes the size so that it fits in the MagSafe socket on the MBP. I get the video from the MBP on the TB display. Then I have a TB cable from the TB Display to an OWC Dock, into which I have 4 USB3 drives and an ethernet cable attached to get me my external drives and ethernet connection to my router. The OWC dock has two TB ports, so I have another cable that goes from it to a second, Belkin, Dock as a backup. Nothing is presently going through the Belkin, although I have a 7 port USB3 hub connected to it for the rest of my deeper storage USB drives.

Yep, it works just fine. I have the TB display set up as a second desktop using the native resolution on the TB. I park five open windows on it: Messages, Mail, Activity Monitor, Calendar and Outlook. Most of my work I do on the MBP native display, but will move things to the TB to park them when I need to do so.

The reason I don't have the other dock running and the other seven drives mounted is that I noticed that the CPU temps with all of those drives attached goes up about 10 degrees. So I only attach them when needed and only for as short a time as I need them. The four that are attached all the time are a TM backup, a CCC clone backup, as second backup for my pictures, and one as a backup of some other important stuff. Backups run each night between midnight and 1 AM. One of the backups is a very small package of a 1TB SSD that I take when I travel as the emergency backup in case anything goes south on me.

But in any case, the TB monitor handles the display and traffic just fine.

 

[chrison600]

The Thunderbolt display is now connected via Apple official Thunderbolt cable from the iMac 27 to the Thunderbolt port on the back of the Thunderbolt display, and still nothing is happening. Is this a dead display?

 

[chscag]

The Thunderbolt display is now connected via Apple official Thunderbolt cable from the iMac 27 to the Thunderbolt port on the back of the Thunderbolt display, and still nothing is happening. Is this a dead display?

There is a possibility that the display is defective although I would think that WOOT checked it out before releasing it for sale.

I did some more research just a while ago about using the TB display with an iMac. There are many examples of how to attach a TB display to a MBP, MBA, and Mac Mini, but very few show anything at all for an iMac.

But what specs there are clearly say that it must be attached via the TB port or it will not work.

Can you tell if the display is powering up at all? I realize there is no fan and it might be difficult to tell if it's powering on. One way to test is turn the display on and attach a USB device (flash drive, etc) to one of the USB 2 output ports to see if any power is going to the device.

 

[chrison600]

I plugged a Lightning cable into the back of the display and it does not indicate as to be charging my iPhone. So I would say the monitor is not getting power or is not reacting to power. I've tried three power cables: The cable that powered the BenQ, the cable that was provided with the Thunderbolt display, and a replica Thunderbolt display power cable I sourced on Amazon.

At this point, I'm guessing the display is dead.

 

[chscag]

Well, sorry to hear that. Hopefully you can return it to WOOT. I've never done business with them so have no idea what their return policy is. Let us know how it all turns out.

 

[chrison600]

I've processed a return to Woot and ordered another Thunderbolt dispay from a seller on eBay. I'll update later once I have the second display.

 

[chscag]

Okay, let us know. I found some additional tips on how to reset a Thunderbolt display that otherwise appears dead. Nothing mentioned about attaching it to an iMac for some reason.

How to Reset Apple's Thunderbolt Display

Apple's Thunderbolt Display, for myriad reasons, may not display an image from your Mac, recognize USB peripherals, connect to Ethernet, or power...

www.macrumors.com

 

[chrison600]

Have you found anything that confirms that the "dock" USB ports will be energized when the monitor is connected to power, regagrdless of whether it's connected to a video source?

 

[chscag]

No, but it makes sense that if the display is not powered up, the USB 2 ports will not provide power to devices attached to them.

Without a video source, the display will be dark but as long as it's attached to AC power and the power supply is good, it should still be able to provide USB power and Firewire power. I expect it will also provide MagSafe power.

What lights up the screen is a video source.

 

[chrison600]

Update: The new/different Thunderbolt display is behaving similarly if not exactly like the previous display. I'm unsure because I did a better job this time diagnosing whether or not the USB ports were powered. If I only connect the Thunderbolt display to power via the included 110v cable, the USB ports in the back of the Thunderbolt display are powered. The moment I connect a Thunderbolt cable, the USB ports turn off. This USB behavior occurs when I use an independent Thunderbolt cable (Apple official) - or - the Thunderbolt cable that is integrated into the display.

Is this an issue with the settings or system of the "host" iMac?

Chris