Lenovo Thunderbolt 4 Dock unboxing and teardown

docking, TB4, teardown, unboxing, USB-C  36 Comments

[Don’t forget to check out the other Thunderbolt 4 Docks]

  1. Introduction
  2. Feature summary
  3. Compatibility notes
  4. Unboxing and component weights
  5. Teardown
  6. PCB
  7. Closeup PCB photos
  8. Analysis
  9. Quirks
  10. Conclusion
  11. More reading

Introduction

I got the Lenovo Thunderbolt 4 Dock on launch day and did a teardown. Here are the results:

Feature summary

  • 135W 3-prong power supply
  • up to 100W USB-C PD charging (limited by PSU and attached devices)
  • 1x HDMI 2.1
  • 2x DP 1.4
  • 1x TB4 downstream port (up to 15W power and DP 1.4 alt mode capable for 4th monitor)
    • Quad monitor capable via MST (not DisplayLink)
    • Dual monitor for older USB-C systems and MacBooks
  • 4x USB 3.2 Gen2 10Gb/s (4.5W power)
  • 1x USB-C 10Gb/s (up to 15W power)
  • 1x Ethernet RJ-45 with 2 modes of operation
    • 2.5GbE Intel i225 PCIe-based works on some Thunderbolt systems
    • 1GbE RealTek 8153 for USB-C systems and incompatible Thunderbolt systems
  • 1x 3.5mm TRRS Audio
  • 1x HDMI 2.1
  • 2x DP 1.4
  • VESA mounting tabs

Compatibility notes

I confirmed that my Surface Book 2 with regular USB-C (DisplayPort 1.2 alt mode) can run at 1x 4K60, 2x 4K30, or 2x 1080p displays on any combination of display output ports. I believe 2x 4K60 is possible on more capable USB-C laptops such as the Surface Book 3 or Surface Pro 7+, but I was unable to confirm given that I don’t have a laptop like that. Otherwise, 3 external screens worked OK with my Thunderbolt-4 enabled Surface Pro 8 (quick video below) and Laptop Studio. I have not tried an external GPU cascaded from the downstream TB4 port but I expect it will work OK. I also did not try a MacBook – but I believe these will be limited to two distinct screens since Mac doesn’t support MST.

Surface Pro 8 on Vertical VESA mount powered by Lenovo TB4 dock (music by maxkomusic.com)

Unboxing and component weights

Typical Lenovo simplicity. The brown corrugated carboard box contained the Dock, TB4 cable, 135W power supply, and AC/mains cable in separate baggies along with user and warranty guides. The power supply with AC/mains cable weighed 541g, the dock 443g, and the ~70cm cable 34g. The chassis is all plastic with a textured finish. While not the heaviest dock, it is heavy enough to make plugging and un-plugging cables relatively easy. USB-C and DisplayPort cables will still need a two-handed approach most of the time, but this is expected for most docks. The AC/mains cable and power supply are 3-prong style which means no “touch current” issues for metal chassis laptops with touch screens.

Teardown

The teardown was straightforward. First, I pulled off 4 rubber pads and the serial number label to reveal 5 Philips (+) 00 screws. Once the screws were removed, I pried off the red panel revealing the PCB. Then I loosened two more Philips 00 screws and unclipped the 4-pin cable for the power button and dislodged a sticky, silver EMI shield. One of the rear-facing USB-C ports held the PCB in place, so I bent the chassis slightly to free it. Once freed, the PCB popped out revealing a machined aluminum heatsink (168g) with attached thermal pads.

PCB

To my surprise, it’s a modular assembly with a separate power regulator daughterboard connected to the mainboard via two 20-pin headers. I suspect the only difference between this model and the 230W workstation model is the daughterboard, included PSU, and host connection cable. A tiny PCB with an illuminated switch was fastened to the main black plastic chassis and connected to the mainboard with a 4-pin cable.

Closeup PCB photos

Note the dozens of test pads likely used for automated testing and a 5-pin header likely used for bench programming the firmware.

Analysis

I love the design of the dock with its modular power regulator – these are the hottest components and most likely to fail so it’s good to know they are easy to replace. Component-wise, here is what I was able to determine:

Here is my best guess of the topology:

Quirks

The Dock includes both Realtek 8153 USB-based and Intel i225 PCIe-based Ethernet components for backwards compatibility with USB-C systems. On my specimen, when plugging in the Dock to a Microsoft Surface Laptop Studio (with TB4), the Intel Ethernet device was not enumerated even after force-installing device drivers and firmware updates, but software components supporting this chip are clearly present in the firmware packages. YMMV. Mac systems and older USB-C based PCs will only be able to drive two independent screens.

Conclusion

Based on the $339 USD list price, this dock, or any other TB4 dock for that matter, isn’t for everyone. But if you need quad monitor support (without DisplayLink) and an array of ports, this is a very capable unit. The only missing feature from this dock compared to others in this category is a UHS-II SD card reader. Most of the competing docks have this feature – so digital photographers without a dedicated high-speed card reader may want to look at those.

More reading

danchar

36 thoughts on “Lenovo Thunderbolt 4 Dock unboxing and teardown”

  1. Hi Danchar

    Glad to see your new teardown post, it’s quite impressive. Especially this kind of non-public model Thunderbolt 4 equipment.

    As I know in early JHL6540 and JHL7440 Models, the downstream Thunderolt port can be configed as DP ports with specific firmware. It seems that Lenovo did the same thing but trans two of the downstream Thunderbolt into DP, to offer the HDMI2.1 and DPs, quite interesting.

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  2. Hi Dan,
    do you use this dock with USB-C devices? Do you have any problems with it?

    I’m looking for a new dock to support both TB3 laptop and USB-C laptop and from my experience there are often stability problems with those docks. Would you recommend this one?

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    • HI Michal, I haven’t used this dock all that much lately, but I have not had any issues with it so far. It’s out of stock most of the time, so if you can snag one, I’d give it a shot.

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  4. Hey regarding the quirks section with the i225 component, I have this dock and I plugged my FreeBSD laptop into it and an “igc0” device shows up and I can use it successfully. igc is the FreeBSD driver for Intel i225 and running pciconf shows it as the intel controller, so I don’t know what FreeBSD is doing differently but its using the intel controller out-of-the-box for me.

    igc manpage: https://www.freebsd.org/cgi/man.cgi?query=igc&apropos=0&sektion=4&manpath=FreeBSD+14.0-current&arch=default&format=html

    pciconf -lv:
    igc0@pci0:134:0:0: class=0x020000 rev=0x03 hdr=0x00 vendor=0x8086 device=0x5502 subvendor=0x8086 subdevice=0x0000
    vendor = ‘Intel Corporation’
    device = ‘Ethernet Controller (2) I225-LMvP’
    class = network
    subclass = ethernet

    ifconfig:
    igc0: flags=8863<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
    options=4e527bb<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,JUMBO_MTU,VLAN_HWCSUM,TSO4,TSO6,LRO,WOL_MAGIC,VLAN_HWFILTER,VLAN_HWTSO,RXCSUM_IPV6,TXCSUM_IPV6,NOMAP>
    ether 04:7b:cb:13:e5:a4
    inet 172.16.0.156 netmask 0xffff0000 broadcast 172.16.255.255
    media: Ethernet autoselect (1000baseT )
    status: active
    nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>
    lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> metric 0 mtu 16384
    options=680003<RXCSUM,TXCSUM,LINKSTATE,RXCSUM_IPV6,TXCSUM_IPV6>
    inet6 ::1 prefixlen 128
    inet6 fe80::1%lo0 prefixlen 64 scopeid 0x2
    inet 127.0.0.1 netmask 0xff000000
    groups: lo
    nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
    pflog0: flags=141<UP,RUNNING,PROMISC> metric 0 mtu 33160
    groups: pflog

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    • Well that’s promising – I wonder why the device doesn’t register in Windows. What host PC are you using? It is UEFI and secure-boot enabled?

      Once the Intel device is enumerated on the bus, can you tell if there is also a Realtek NIC device present?

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  5. As per this page (couldn’t include link), drivers and software, it appears that the Realtek eth is over USB, and the Intel eth is over pcie. Lenovo also has a list of systems that the intel chip will work with at (couldn’t include link). I hope this dock is available to ship again soon in the workstation version.

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  6. Appologies for the repost. Had to login for links to work.
    As per this page (https://support.lenovo.com/ca/en/accessories/pd500533-thinkpad-thunderbolt-4-workstation-dock-overview-and-service-parts), drivers and software, it appears that the Realtek eth is over USB, and the Intel eth is over pcie. Lenovo also has a list of systems that the intel chip will work with at (https://download.lenovo.com/pccbbs/mobiles/pcieeth01w.txt). I hope this dock is available to ship again soon in the workstation version.

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    • Glad you got it working. I still can’t get the Intel i225 working with my Surface Laptop Studio and Lenovo dock. running Windows 11. All firmware and drivers are updated but the Intel device just won’t enumerate on the bus. The Realtek device works fine.

      I suspect that the dock’s firmware has a bug to set a flag to USB-C compat mode if the first laptop you plugged in after a firmware update was not a Thunderbolt-4 device.

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    • Thanks Miguel.
      I’m not sure about Mac compatibility with the Lenovo dock – it’s not specifically advertised as Lenovo has their own PC brand to worry about. I suspect it will work fine, but Lenovo probably won’t offer any product support for it. The older Thunderbolt 3 dock worked OK but with some limitations on the monitor outputs due to Mac not supporting MST so you will have to use an adapter for the downstream TB4 to get a second distinct monitor working on Mac like the older TB3 Dock. Please see: https://www.youtube.com/watch?v=SpjYKy3AiW4

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  10. Hi Dan, thanks for this article. I just received a Lenovo ThinkPad Thunderbolt 4 Dock Workstation Dock 40B00300EU and am trying to run 3 external displays along with my Surface Book 3 display, but I can only get 3 displays working at a time. When I try and extend the desktop to the 4th display one of the other ones is disabled.

    Any ideas what’s going worng?

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      • Thanks Dan, I had that setup with a Surface Dock 2 and the performance of the laptop was terrible, especially when using Teams (literally not able to use any other application). I wondered if the DisplayLink was playing a part. Using the Lenovo dock and DisplayLink I now have 3 external and the laptop screen going but the performance is also pretty poor. When I remove the DisplayLink and use the 3 external monitors without the laptop it works ok. Although from time to time one of the screen flickers and I have to disconnect and reconnect. I guess the Surface Book isn’t quite up to the job!

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  11. Could anyone verify what the connector to the “SW LED BOARD” is? I don’t have such a Dock yet. It looks like a 5 pin Molex Picoblade, which would be the same as in the Ultra Docking Station (40AJ). Thanks.

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  12. Hi Dan, thank you so much, hugely helpful article.
    I’m trying to use the same docking setup for my personal Surface Laptop Studio, and my work Thinkpad. Will this do the job? I assume I’ll need a Surface charging cable for my Laptop Studio while using any thunderbolt dock?

    Thanks in advance,

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  13. Hey Dan or anyone else with this dock.
    Has anyone been able to get a single 4k monitor working at 120hz or 144hz?

    In the docks comparison article it’s mentioned that sometimes extra display modes are not listed and Lenovo support only has 4k@60hz listed for this dock.
    Unfortunately, in testing with latest 1.0.11 firmware, I’m unable to get anything higher than 4k 60hz via both DP and HDMI2.1. I did try both DP ports on the dock and verified that via direct GPU I can reach 120/144hz.

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    • I don’t have the proper monitors to test, but if you can’t get it working on the built-in DP or HDMI ports, try the sole Thunderbolt port on the dock along with a USB-C -> DP or USB-C -> HDMI 2.1 adapter.

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      • Thanks, I got such a cable and I can confirm it works at 144hz.
        No idea why this would be the case, but it is what it is.

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  17. Has anyone managed to get the 2.5Gb ethernet working with a non-Lenovo Thunderbolt 3/4 device? I’ve tried Dells without any luck, but it does work with a Lenovo T14, so the dock doesn’t have any issues enabling it for a “compatible” device.

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  18. The structure is not correct. The Fresco FL5801 is usually connected a) with two upstream ports (one on the Type C USB 2.0 lanes, one on the JHL8440 USB 2.0 downstream) or b) connected with one upstream port to a Mux switchting between Type C USB2.0 and JHL8440. This is required for TBT3 backwards compatibility. TBT4 does not support USB2.0 being tunneled like TBT3 does. Thus, USB2.0 must be connected directly to the Type C upstream ports.

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  19. I took apart a Workstation model of that dock. Surprisingly it’s an exact match. Not even the daughterboard is different. So, the only differences between the two models are: Label, Power adapter, Host cable.

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