Surface Pro 3 dock not detecting external monitor

Some more observations in case it helps:

• When I unplug the Apple MDP-DVI adapter from the SP3 I hear three tones with decreasing pitch.  I take this to mean SP3 has recognized the adapter has been unplugged.  The SP3 then changes so that it becomes the main screen (previously the monitor connected to the adapter was the main screen).
• When I plug the Apple MDP-DVI adapter into the dock I hear three tones with increasing pitch.  I believe this means that the dock is detecting the adapter's presence.  The external monitor then displays a stable blue background, which I believe means the monitor has synced to the proper resolution.  The SP3 also changes so that it becomes the secondary monitor.  However the external (now main) monitor does not display any image.

Given my experimentation and from what Ive found on the web I am developing a hypothesis.  If the web sources are correct Apple's adapter is a Thunderbolt device containing an internal chip.  The chip's purpose is to dynamically alter the cable's electrical characteristics to allow higher bandwidth while minimizing signal degradation.

My hypothesis is that the dock works correctly with "dumb" pass-through adapters but not with active adapters containing embedded electronics (caveat - I am not familiar with either the MDP or DVI standards).  This might explain why the sync signals reach the monitor but not the video signal.  The reason Apple's MDP-VGA adapter works may be due to VGA's analog nature. 

My 2c FWIW,

Steve

I too had this problem and found a solution.  In my case my external monitor worked when connected to the SP3 but did not work connected to the dock.  I have an HP w2007 monitor (DVI) connected to an Apple DVI to miniDisplayPort adapter.

After doing some googling I discovered Apple's adapter is an active device containing internal chips.  After replacing the Apple adapter with a different one manufactured by RocketFish the monitor now works with the dock as well as with the SP3.

Bottom line - if your monitor doesn't work with the dock but does work with the SP3 try replacing your miniDisplayPort adapter.  It appears that Apple's adaptor (Thunderbolt) is not compatible with the dock.

Steve Neis,

I couldn't get a branded one here in Dubai (Except for the Apple one which I cant get to work on the Docking station) , so not wanting to be beat on this I took both the SP3 and docking station to a local PC shop.

After a few minutes of testing this is what I have .

A straight pass through lead connected to the docking station and I have video output, everything works fine, however when I connect the same lead directly to the SP3 I have no video output?

Not really an issue though as the docking station is now doing what it should.

In short there are 3 types of cable I have found,

Mac Lead : works with direct connection to the SP3 but now with the docking station

None Branded #1 lead : Same as above ( I actually suspect this was simply a Mac copy)

None Branded #2: lead works with docking station but not with SP3 direct connection

The guy couldn't tell me what the difference between the 2 none branded leads were, and simply stated that there are 3 types. but I suspect one of them was a Mac copy although physically 1&2  looked the same.

I guess its all trial and error, but i'm happy now and this is a very special piece of kit :)

Thanks Steve because you pointed me in the right direction.

3 weeks in and still nothing.

Absolutely unacceptable. The whole point of buying the docking station is to eliminate plugging things in every time I move from one desk to the other.