How timely! My teardown of Linksys’ VLP01 router, submitted in late September, was published one day prior to when I started working on this write-up in late October.

What’s the significance, aside from the chronological cadence? Well, at the end of that earlier piece, I wrote:

There’s another surprise waiting in the wings, but I’ll save that for another teardown another (near-future, I promise) day.

That day is today. And if you’ve already read my earlier piece (which you have, right?), you know that I actually spent the first few hundred words of it talking about a different Linksys router, the LN1301, also known as the MX4300:

I bought a bunch of ‘em on closeout from Woot (yep, the same place that the refurbished VLP01 two-pack came from), and I even asked my wife to pick up one too, with the following rationale:

That’ll give me plenty of units for both my current four-node mesh topology and as-needed spares…and eventually I may decide to throw caution to the wind and redirect one of the spares to a (presumed destructive) teardown, too.

Last month’s bigger brother

Hold that thought. Today’s teardown victim was another refurbished Linksys router two-pack from Woot, purchased a few months later, this February to be exact. Woot promotion-titled the product page as a “Linksys AX4200 Velop Mesh Wi-Fi 6 System”, and the specs further indicated that it was a “Linksys MX8400-RM2 AX4200 Velop Mesh Wi-Fi 6 Router System 2-Pack”. It cost me $19.99 plus tax (with free shipping) after another $5 promotion-code discount, and I figured that, as with the two-VLP01 kit, I’d tear down one of the two routers for your enjoyment and hold onto the other for use as a mesh node. Here’s its stock image on Woot’s website:

Looks kinda like the MX4300, doesn’t it? I admittedly didn’t initially notice the physical similarity, in part because of the MX8400 product name replicated on the outer box label:

When I started working on the sticker holding the lid in place, I noticed a corner of a piece of literature sticking out, which turned out to be the warranty brochure. Nice packing job, Linksys!

Lifting the lid:

You’ll find both routers inside, along with two Ethernet cable strands rattling around loose. Underneath the thick blue cardstock piece labeled “Setup Guide” to the right:

are the two power supplies, along with…umm…the setup guide plus a support document:

Some shots of the wall wart follow:

including the specs:

and finally, our patient, as usual, accompanied by a 0.75″ (19.1 mm) diameter U.S. penny for size comparison purposes. Front view:

left side:

back, both an overview and a closeup of the various connectors: power, WAN, three LAN, and USB-A. Hmm…where have I seen that combo before?

right side:

top, complete with the status LED:

and…wait. What’s this?

More than one way to “skin a cat”

In addition to the always-informative K7S-03580 FCC ID, check out that MX4200C product name. When I saw it, I realized two key things:

• Linksys was playing a similar naming game to what they’d done with the VLP01. Quoting from my earlier teardown: “…an outer box shot of what I got…which, I’ve just noticed, claims that it’s an AC2400 configuration (I’m guessing this is because Linksys is mesh-adding the two devices’ theoretical peak bandwidths together? Lame, Linksys, lame…)” This time, they seemingly added the numbers in the two MX4200 device names together to come up with the “bigger is better” MX8400 moniker.
• The MX4200(C, in this case) is mighty close to MX4300. Now also realizing the physical similarity, I suspected I had a near-clone (and much less expensive, not to mention more widely available) sibling to the no-longer-available router I’d discussed a month earlier, which, being rare, I was therefore so reticent to (presumably destructively) disassemble.

Some background from my online research before proceeding:

• The MX4200 came in two generational versions, both of them integrating 512 Mbytes of flash memory for firmware storage. V1 of the MX4200 included 512 Mbytes of RAM and had dimensions of 18.5cm (7.3 inches) high and 7.9cm (3.1 inches) wide. The larger, 24.3cm (9.57 inches) high and 11cm (4.45 inches) wide, V2 MX4200 also doubled the internal RAM capacity to 1 GByte.
• This MX4200C is supposedly a Costco-only variant (meaning what beyond the custom bottom sticker? Dunno), conceptually reminiscent of the Walmart-only VLP01 I’d taken apart last month. I can’t find any specs on it, but given its dimensional commonality with the V2 MX4200, I’ll be curious to peer inside and see if it embeds 1 GByte of RAM, too.
• And the MX4300? It’s also dimensionally reminiscent of the V2 MX4200. But this time, there are 2 GBytes of RAM inside it. Last month, I’d mentioned that the MX4300 also bumps up the flash memory to 1 GByte, but the online source I’d gotten that info from was apparently incorrect. It’s 512 GBytes, the same as in both versions of the MX4200.

Diving in

Clearly, now that I’m aware of the commonality between this MX4200C and the MX4300, I’m going to be more careful (but still comprehensive) than I might otherwise be with my dissection, in the hope of a subsequent full resurrection. To wit, here we go, following the same initial steps I used for the much smaller VLP01 a month ago. The only top groove I was able to punch through was the back edge, and even then, I had to switch to a flat-head screwdriver to make tangible disassembly progress (without permanently creasing the spudger blade in the process):

Voila:

Next to go, again as before, are those four screws:

And now for a notable deviation from last month’s disassembly scheme. That time, there were also screws under the bottom rubber “feet” that needed to be removed before I could gain access to the insides. This time, conversely, when I picked up the assembly in preparation for turning it upside-down…

Alrighty, then!

 

Behold our first glimpses of the insides. Referencing the earlier outer case equivalents (with the qualifier that, visually obviously, the PCB is installed diagonally), here’s the front:

Left side:

Back, along with another accompanying connectors closeup (note, by the way, the two screws at the bottom of the exposed portion of the PCB):

And right side:

Let’s next get rid of the plastic shield around the connectors, which, as was the case last month, lifted away straightaway:

Heat-removal hardware removal

And next, the finned heatsink to its left (in the earlier photo) and the rear right half of the assemblage (when viewed from the front):

We have liftoff:

Oh, goodie, Faraday cages! Hold that thought:

Rotating the assemblage around exposes the other (front left) half and its metal plate, which, with the just-seen four heatsink screws also no longer holding it in place, lifts right off as well:

You probably already noticed the colored wires in the prior shots. Here are the up-top antennas and LED assembly where they end up:

And here’s where at least some of them originate:

Unhooking the wire harness running up the side of the assemblage, along with removing the two screws noted earlier at the bottom of the PCB, enables the board’s subsequent release:

Here’s what I’m calling the PCB backside (formerly in the rear right region) which the finned heatsink previously partially covered and which you’ve already seen:

And here’s the newly-exposed-to-view frontside (formerly front left, to be precise), with even more Faraday cages awaiting my pry-off attention:

Dissecting cage contents

I’m happy to oblige. Upper left corner first:

Temporarily (because, as previously mentioned, I aspire to put everything back together in functionally resurrected form later) bend the tab away, and with thanks to Google Image search results for the tip, a Silicon Labs EFR32MG21 Series 2 Multiprotocol Wireless SoC, supporting Bluetooth, Thread, and Zigbee mesh protocols, comes into view. The previously shown single-lead antenna connection on the other side of the PCB is presumably associated with it:

To its left, uncaged, is a Fidelix FMND4G08S3J-ID 512 Mbyte NAND flash memory, presumably for holding the system firmware.

Most of the rest of the cages’ contents are bland, unless you’re into lots of passives; as you’ll soon see, their associated ICs on the other side are more exciting:

Note in all these so-far cases, as well as the remainder, that thermal tape is employed for heat transfer purposes, not paste. Linksys’ decision not only makes it easier to see what’s underneath it will also increase the subsequent likelihood of tape-back-in-place reassembly functional success:

And after all those passives, the final cage at bottom left ended up being IC-inclusive again, this time containing a Qualcomm PMP8074 power management controller:

Now for a revisit of the other side of the PCB, starting with the top-most cage and working our way to the bottom. The first one, with two antenna connectors notably above it, encompasses a portion of the wireless networking subsystem and is based on two Qualcomm Wi-Fi SoCs, the QCN5024 for 2.4 GHz and QCN5054 for 5 GHz. Above the former are two Skyworks SKY85340-11 front-end modules (FEMs); the latter is topped off by two Skyworks SKY85755-11s:

C = Costco = capacity-reduced?

The next cage is for the processor, a quad-core 1.4 GHz Qualcomm IPQ8174, the same SoC and speed bin as in the Linksys MX4300 I discussed last month, and the volatile memory, two ESMT M15T2G16128A 2 Gbit DDR3-933 SDRAMs. I guess we now know how the MX4200C differs from the V2 MX4200; Linksys halved the RAM to 512 GBytes total, reminiscent of the V1 MX4200’s allocation, to come up with this Costco-special product spin.

The third one, this time with four antennae connectors below it, houses the remainder of the (5 GHz-only, in this case) Wi-Fi subsystem; four more Qualcomm QCN5054s, each with a mated Skyworks SKY85755-11 FEM:

And last but not least, at bottom right is the final cage, containing a Qualcomm QCA8075 five-port 10/100/1000 Mbps Ethernet transceiver, only four ports’ worth of which are seemingly leveraged in this design (one WAN, three LAN, if you’ll recall from earlier). Its function is unsurprising given its layout proximity to the two Botthand LG2P109RN dual-port magnetic transformers to its right:

And with that, I’ll wrap up for today. More info on the MX4200 (V1, to be precise) can be found at WikiDevi. Over to you for your thoughts in the comments!

—Brian Dipert is the Principal at Sierra Media and a former technical editor at EDN Magazine, where he still regularly contributes as a freelancer.

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