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Surface Pro 3 landscape docking station teardown (part 2)

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Comments (19)
  1. mike says:

    aloha dan!

    i'm glad you did this one as well, i was wondering what was in there!

    your last post helped me out quite a bit; I've been looking to mod my dock as I am not a fan of the angle it sits at, and just wanted a more portable way to carry around my dock (the odd shape doesn't really fend well in luggage/gear bag). basically I ripped it apart to step 3, got rid of the backing, and put it back together. (here:…/4ApSFAFphr )

    for my purpose, I took the magnet from the left side and added it to the black molding behind the connector… i was thinking of adding another small magnet back there as well for good measure (…/ref=sr_1_14) just to ensure a good solid pull.

    anyway, i was just curious: in your professional opinion, do you think the magnet placement and/or adding another magnet would have adverse effects? it seems to be shielded well, it's performing as it should, and i am getting no additional noise (i produce music for a living), but i figure someone who does this on your level would have better insight.

    again, thanks for your time. like you i am an avid supporter of the surface pro 3 and have been using it almost since launch a year ago, despite colleagues of mine thinking i'm lying or just being in pure disbelief when i show them haha

    cheers! -mike

  2. Danchar4 says:

    Glad its working for you Mike and thanks for sharing the pic. Very cool. Just checking out your soundcloud now… I don't think adding the magnets would have any adverse effects so I think you should go for it! But make sure those little magnets are glued on really tight – you don't want kids or pets getting ahold of them.

    When you get a chance, can you share a full picture of your desktop with external monitors and audio gear? I'm really curious to see how you're using everything together.



  3. mike says:

    dan thanks for the reply! sorry i didn't realize you responded to both. will do when I have a chance!

  4. mike says:

    Aloha Dan,

    here's a link to my temporary setup with pics of the dock mod (it's not pretty and neatly finished but I will eventually get around to making it all spiffy).…/AABtTbii9cHDR0ct41q8JQlpa

    also i just moved so when I get the full setup going ill make sure to keep you updated!

  5. mike says:

    idk if you had anything to do with the new dock for the sp3/4/book, but nonetheless thank you to you and ms team!

  6. Danchar4 says:

    Mike, thanks for the comments. No I did not have anything to do with the new dock. But I played with it last week and like it a lot. It ought to work great for your scenario and integrate into other solutions quite well.

  7. Jess says:

    Thanks for the tear down. I recently bought a surface pro 3 to replace my surface pro, I already have a Targus dock and would love to just use the 40 pin connector for USB3.0 and power.  I have scoured the net looking for an adapter that includes the USB but they only seem to have power.  Do you know of any?  

  8. Danchar4 says:


    As far as I know, there are no vendors offering the solution you describe.

    What some folks do is get the MS docking station and plug the Targus into it to get additional ports and monitor outputs. I have tried this approach and it works, but its a lot of boxes and cables on your desk. You could always sell the Targus and buy the MS dock…

    Just out of curiosity, how much would you be willing to pay for a converter cable that had the 40-pin connector with magnets on one end and a receptacle for 12V power and a USB 3.0 port on the other end?

  9. Jess says:

    Thanks for the quick reply.

    I was thinking around $40 to save buying another dock for $200. The new MS dock for the surface 4 looks perfect…/productID.325725200

    If you have no plans for the 40 pin connector you pulled from the dock I am an electronic engineer so I'd happily buy the bits from you and experiment with them. Otherwise it looks like I'll be buying a new dock. Thanks

  10. Danchar4 says:

    @Jess, I messed up the connector – you don't want mine even if you have reflow tools etc. You might want to bid on this broken dock and just do your own teardown:…/252141202319

  11. Mikhael says:

    Hi Danchar,

    Do you have any new information regarding the dock connector pinout? I disassembled the dock station to the level of the connector with cables. I found USB pins, but Display port data is not connected directly to pins, I assume, the small board have a drivers/buffers (probably, you assumed that it is ESD protectors). Also I cannot define power (2 pins from each corner).

  12. Danchar4 says:


    The connector spec is proprietary and provided to partners who sign an agreement with Microsoft as part of the Designed for Surface Program. To get the full spec, apply here:…/partner-sign-up

    That being said some of the pins are certainly easy to reverse engineer – just very tedious. I do remember that by simply following traces on the little board, there was some symmetry involved which led me to believe it was a reversible connector (confirmed with the release of SurfaceBook and the new Surface Pro 4 docking station) So the high-speed lines like USB super speed and DP ML must be grouped together and the DP AUX/HPD/CONFIG and USB 2.0 low-speed lines must be grouped together. That way when you flip the connector, the same wires are always used for high-speed data vs low-speed data (high-speed pairs and low-speed pairs have different specs)

    We know DP has 4 pairs of high speed, 1 AUX low speed and some control pins like HPD/CONFIG. USB3 has 2 pairs of high speed and 1 pair of low speed. So we have 6 pairs of high speed total and 3 or 4 pairs of low speed. From trivial inspection we know that every 3rd contact is ground.

    So if you run down one side of the connector it should be something like this:

    +12v, power hot plug thingy, ground, highspeed data, highspeed data, ground, highspeed data, highspeed data, ground, highspeed data, highspeed data, ground, lowspeed data, lowspeed data, ground, lowspeed data, lowspeed data, ground, power hot plug thingy, +12v

    And the other side would be the reverse order so when you flip the connector everything matches up.

    The polarity of the differential pairs would have to be consistent for a reversible connector as well. So if you mapped out USB, you already know the polarity of all other differential pairs. You just need to map out which DP ML lanes are which.

    I think the DP HPD pin was straight through. DP Config pin I already explained as coming out that little 3-pin connector and grounded through a 1Meg resistor on the dock motherboard. So deducing which lanes are DP AUX is easy.

    If you want to figure out how the power hot-plug thingy contacts work, try cracking open a $10 knockoff power brick from ebay.

    Hope that helps.

  13. Mikhael says:

    Hi Danchar,

    Thank you for your quick and complete reply.

    We already signed the NDA with MS. They promised to join us to their customer program, I got contacts and 1st reply, and after this, about 3 months I don't receive any answer on my repeating questions.

    Anyway I did reverse engineering and defined following pinout:

    Pin Signal Destination             Pin Signal Destination
    1 +PWR PWR con/6, 7                2 +PWR PWR con/6, 7
    3 HPD1B (Sense?) Pwr con /3        4 ???
    5 GND                              6 GND
    7 DP ML_Lane0(p) MiniDP /3         8 USB D- USB/2
    9 DP ML_Lane0(n) MiniDP /5        10 USB D+ USB/3
    11 GND                            12 GND
    13 DP ML_Lane1(p) MiniDP /9       14 NC
    15 DP ML_Lane1(n) MiniDP /11      16 DP Hot Plug Det MiniDP /2
    17 GND                            18 GND
    19 DP ML_Lane2(p) MiniDP /15      20 DP ML_Lane3(n) MiniDP /12
    21 DP ML_Lane2(n) MiniDP /17      22 DP ML_Lane3(p) MiniDP /10
    23 GND                            24 GND
    25 DP Config 1 MiniDP/4           26 USB Stda_SSRX- USB/5
    27 NC                             28 USB Stda_SSRX+ USB/6
    29 GND                            30 GND
    31 DP AUX_CH(p) MiniDP /16        32 USB Stda_SSTX- USB/8
    33 DP AUX_CH (n) MiniDP /18       34 USB Stda_SSTX+ USB/9
    35 GND                            36 GND
    37 ???                            38 HPD1A (Sense?) Pwr con /5
    39 +PWR PWR con/6, 7              40 +PWR PWR con/6, 7

    DP ML_LaneX(p, n) are routed via differential drivers according application notes

    As I assume, HPD1A, B are connected to +PWR via any resistor inside the SPro3. Do you know, are they joined by OR gate or are checked separately? What is a condition to Power ON? (when no SPro, the power is "hicking"). The HPD2, power connector pin 4, I did not found coming to the SPro connector. What is his function?

  14. Danchar4 says:

    Wow nice work Mikhael! Thanks for sharing your findings.

    Sorry to hear about the lack of response from the program. Not sure what's going on there.

    I think pin 4 and 37 in your chart are the "HPD2" function printed on the little circuit board. I had trouble following the connections with all the little vias so I'm not exactly sure what's going on but its likely a feedback mechanism to control power delivery to the tablet.

    What is your goal here?

    Do you want to 100% reproduce the charging scheme implemented in the MS brand docking station? Or do you want to just get the tablet to charge?

    There is a simple way to get the tablet to charge with your own power supply: you can buy a "Surface Pro 3 charge cable" on ebay for ~$5 that will convert from an industry standard barrel connector to the 12-pin surface connector. IIRC all that is inside these knock-off assemblies are a couple FETs, a couple resistors and an LED but I don't remember the layout. Just like Apple Mag-safe and Samsung chargers, there is likely a resistor with a very specific value that indicates the expected peak current to the tablet. So open up one of those cables to find the value. Also see if you can find old posts from "Mikegyver" in google cache or waybackmachine. I think he actually documented some of this at one time but I can't seem to find his posts any more.

    Keep in mind that with these types of connectors you always have the risk of hot-plug high-current arcing that will destroy the tiny traces over time. So you really want a robust feedback scheme to mitigate that risk. If you monitor the +12v and HPD lines as you connect the tablet to the MS charger with an ammeter and oscilloscope, you may be able to see a feedback mechanism in action.

  15. Mikhael says:

    Hi Danchar,

    I will integrate the tablet in my device. For this purpose I will develop my own communication board communicating with Spro via docking connector. I even don't need to reproduce the charge control, because the device works from its own power supply that also will power the tablet all the time when is turned ON. Also, since the tablet will be embedded and not detachable, the hot plug is not actual.

    BTW, I still did not found the connector similar to docking one. Do you know, is it any off-the-shelf part, or a MS custom designed one?

  16. Danchar4 says:

    Hi Mikhael,

    Sounds like a very cool project! Sadly, the connectors are 100% Microsoft proprietary and only licensed partners can pull from the MS supply chain.

    Do you have the physical space to just include the MS dock circuit board with your solution? The brand new Surface Pro 4 dock also works on Pro 3 and is quite compact. You can disassemble it to remove the lead weight inside  – the circuit board is tiny with much less Z-height than what you'd think by its case. Its power supply is still rather large, but not too bad.

  17. Mikhael says:

    Hi Danchar,

    This is only a relatively small part of my project:)

    Unfortunately I cannot use a docking station board as it is, I must design my proprietary one to provide all required functions to communicate between the Spro 3 and my device. MS persons that I got their names for contact for this program, still don't answer me after a lot of my repetitive mails.  

  18. Thierry P says:

    Hello folks,

    following your research, do you think it’s possible to use the surface connect port to plug a USB-C external GPU device ?

    1. Danchar4 says:

      Thierry, unfortunately you won’t be able to use an external GPU with the connector on the SP3/SP4. Sound like you might want to trade up to the Surface Book!

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