Bill-of-materials secrets may not make it into product documentation but are unlikely to survive teardown scrutiny.
I recently stumbled across a technique for cost-effectively obtaining teardown candidates, which I definitely plan to continue employing in the future (in fact, I’ve now got two more victims queued up in my office which I acquired the same way, although I’m not going to spoil the surprise by telling you about them yet). I’d long had a hankering to take apart an Apple HomePod mini smart speaker, as a follow-on to my multiple already-published teardowns of various Amazon Echo and Google (Nest) Home devices.
Brand new HomePod minis cost $99, though, with fully functional used ones selling for not much less than that on eBay. The key words in that prior sentence, however, are fully functional. Recently I stumbled across two posted on eBay from the same seller, one white in color and the other space grey, for $30 each plus $10 each for shipping (albeit neither with the 20W USB-C power adapter included with new units). They were both described as:
Parts Only. Cord is Ripped. Speaker in Great Condition.
Sound perfect for teardown purposes, right? I ended up buying them both for $30 each inclusive of shipping. And although I expected from the descriptions that neither would be functional on arrival, it turns out the space grey one works fine (which is how I can confidently testify to the sound quality in the title of this piece), although its power cord was definitely beaten up. I’m guessing that either a pet’s teeth or a vacuum cleaner beater bar had mangled it…nothing that some electrical tape wrapped around the cosmetic damage couldn’t re-protect.
The white one, however, was definitely DOA. Here’s a stock photo of what it theoretically would look like in operation, complete with the psychedelic color pattern topside:
And here’s mine, as usual accompanied by a United States penny (0.75 inches/19.05 mm in diameter) for size-comparison purposes (per the specs, the HomePod mini is 3.3 inches/84.3 mm high, 3.9 inches/97.9 mm wide, and weighs 0.76 pound/345 grams):
Coffee stains? Dunno (one of several examples across the entire cable span):
And finally, definitely-more-than-cosmetic damage:
Here’s a closeup, in case you had any lingering doubts:
At this point you might be asking, “Why didn’t you just replace the shredded cord, Brian?” A fair question. Unfortunately, however, unlike with the larger standard HomePod sibling (for which replacement is possible, although Apple doesn’t make it easy…and which ironically got resurrected by Apple just as I was finalizing this writeup), the HomePod mini’s power cable isn’t detachable. And although some clever hacking might deliver a homegrown alternative, it’s definitely not an Apple-sanctioned replacement part. Obsolescence by design, indeed:
Time to dive in. That sticker attached to the underside looks like an encouraging portal:
No screws yet (although we now know the FCC ID, BCG-A2374, along with the power input specifications, 9.V@2.22A):
Just a bit of glue; nothing that a thin flat-head screwdriver can’t tackle:
They’re not just Torx head screws; they also have rubber washers around them:
Another, beefier Torx screw begs for removal, too:
We’re not yet inside, but at least now I can start removing the “perfectly seamless mesh fabric that’s virtually transparent to the sound passing through it,” to quote Apple’s promo prose. Interestingly, at least to me, it’s a dual-layer “sock” approach:
See those rubber oval pieces around and near the bottom (which is at the top in these device-upside-down shots)? You know what comes next:
Whaddya know, more Torx screws!
Ever wonder what it looks like when a Torx driver slips off the screw head and into the hand of the person holding the device being disassembled? Wonder no more (I do it all for you, dear readers…don’t worry, it was just a flesh wound):
Time to get out that thin flat-head screwdriver again (PS…see those scrapes? They aren’t caused by the flat-head screwdriver; they’re from my earlier Torx slip-and-pierce debacle):
In the process of striving to pry open the HomePod mini, I discovered that although the power cord can’t itself be detached, the mesh-attached ring around the power cord can be:
Although the mesh is still attached at the top, the result is a bit cleaner view of the chassis (along with left-over blood deposited on the mesh by my earlier debacle):
And speaking of “prying open”, I only got the chassis partway open. The power cord internally routes toward the top, and I didn’t want to cut it, nor did I desire to snip the flex cable also headed in that same direction:
At that point, I revisited the now-less-mess-obscured remainder of the chassis and saw four more oval rubber pieces…along with three circular regions, underneath which I’m betting are MEMS microphones (although the product specs list four total mics…hold that thought).
Here we go again, this time hopefully with no further flesh punctures or blood loss:
Back to the flat-head screwdriver to surmount the lingering adhesive hold:
And we’re finally in!
Let’s take in the “lay of the land” before proceeding. Again, you’re looking at the inside of the top portion of the device. At top is the translucent (so that the multicolor LEDs below it can shine through to the outside) capacitive touch panel, held in place by a four-screw bracket, with an additional three holes for the mics. The touch panel is ribbon cable-connected to the PCB underneath it, also containing three corresponding mic holes (presumably, as we’ll be able to confirm shortly, the MEMS mics themselves are on the other side of the PCB). And on top of the PCB is a partial-sphere translucent diffuser; you can faintly see the LED array underneath it.
Here’s a closer look at the capacitive touch panel assembly:
Now let’s get those bracket screws off:
Leaving us with standalone views of the touch panel, from the outside:
Next, the PCB:
which is encircled by a thin rubber gasket:
Turns out, the lightly glued diffuser pops right off:
leaving us with a much more interesting view of the PCB’s contents:
There are, if I’ve counted correctly, 19 total LEDs. That small rectangular object next to one of them at the bottom of the array is, iFixit tells me, an ambient light sensor from Austria Microsystems. The two rectangular ICs are Texas Instruments LP5030 30-channel constant current RGB LED drivers, and the smaller square one is a TI TPS55340 5A/40V boost regulator.
My, what big capacitors you have:
Remember me mentioning before that the power cord was non-removable, therefore non-replaceable? Here’s why: it ends up here, attached to the PCB via a proprietary connector:
With it detached, the other side of the PCB comes into full view:
Again, let’s do an overview before focusing on minutia. At the top of the picture is the remaining lower portion of the HomePod mini, containing (among other things) the speaker. You can see the positive and negative leads coming out of it, ending in circular terminals that are clip-attached to the plastic bracket and press-connected to circular contacts on the PCB (and held in place by two of the four screws I recently removed to get to this point). I’d earlier shown you the power cord and a separate ribbon cable heading upwards to this point; the ribbon cable is still attached (don’t worry; its functions will become apparent shortly).
Speaking of which, let’s detach that ribbon cable to fully free the PCB from its captivity:
Phew, that’s better. Let’s begin with four angle-view shots to, among other things, showcase the earlier-glimpsed capacitors in all their lofty magnificence:
One of the things that likely caught your eye in the earlier overview shot was the rectangular two-chip (plus passives, etc.) structure:
The smaller IC at the top, again with kudos to iFixit and its community for their sleuthing, is an Apple 338S00553-A0, which handles various system power management functions and was reportedly co-developed with Dialog Semiconductor. Underneath it is Apple’s S5 SoC, interestingly (at least to me) a chip normally found in the Apple Watch. It’s the system processor, handles all audio processing functions, and also contains an estimated 1 GByte of LPDDR3 SDRAM. Other ICs visible in this image include:
The ICs here are, unsurprisingly given their shielded status, both RF-focused in function. At the upper right is the smaller Skyworks SKY66404-11 2.4 GHz front-end module for Zigbee, Thread, and Bluetooth, and the larger one in the lower left is Nordic Semiconductor’s nRF52833 Bluetooth 5.3 SoC with Bluetooth Low Energy and mesh, NFC, Thread and Zigbee support (seemingly redundant with the Bluetooth facilities in the earlier mentioned Apple-developed/USI-branded 339M00117 module). Go back and look at the earlier PCB other-side overview image and you’ll see the embedded antennas for Bluetooth and other 2.4 GHz stuff.
One more closeup to go, this of one of the three MEMS microphones, reportedly supplied by Goertek, and symmetrically located on the edge of the PCB:
And before moving on, let’s zoom the camera out for one final PCB wide-angle overview shot:
Now for the rest of the system (and story):
The speaker assembly pops right out of the surrounding chassis:
Those widgets on either side of the chassis aren’t amplifier-driven active speaker drivers, they’re supplemental passive radiators, which in Apple parlance are “force‑cancelling” to “give HomePod mini incredible bass extension” (the flexible rubber assemblage around each gives ‘em “bounce”).
As for the speaker itself:
Let’s get those four screws off:
These are the areas whose cone movement directly affect the passive radiators to either side:
And finally, the cone (and more general transducer) itself. Apple promo jargon again: this “Apple-designed full‑range driver uses an incredibly powerful neodymium magnet to deliver deep bass and crisp high frequencies”:
That assemblage underneath it, which also forms the base of the device, is a waveguide. Over to Apple’s marketeers for more: “The unique acoustic waveguide directs sound out the bottom of the speaker, creating a 360‑degree audio field for consistent sound no matter where you are in the room”:
And hey, we’re almost done! Here’s the other reason why the power cord isn’t removable; it’s in-place reinforced by a two-screw bracket:
And last, but definitely not least, what’s with that ribbon cable’s other end? Carefully pull it out:
and you’ll find two things: the aforementioned fourth MEMs microphone (which with the others “work together to help cancel noise and listen for “Hey Siri” — even if your environment is loud, you don’t have to turn the volume down or move closer to be heard.”), and (at the very end of the cable) a TI HDC2010YPA humidity and temperature sensor.
Waa? Once again, I’ll cue irony. And by means of explanation, I’ll use an analogy. As I first mentioned back in late 2018, the first-generation Amazon Echo also came in a “Plus” variant, several of which I still have in inventory, which supported limited Zigbee “smart home” automation capabilities. But at least Amazon promoted them. The Zigbee facilities in the first-generation Google OnHub routers made by partners ASUS and TP-Link, as I first mentioned in mid-2020, never even got enabled (and were only barely and obscurely even documented) prior to the products’ obsolescence late last year.
Seems the same thing is going on here, although the fruits of Apple’s smart home aspirations, which have silently languished for more than two years, may yet ripen and see the light of day. Not only did Apple (as I mentioned earlier) announce a second-generation HomePod today, just as I was finishing up this writeup, the company also finally publicly fessed up to the longstanding inclusion of an environmental sensor in the HomePod Mini, indicating that it would find use (after unlock via an upcoming firmware update) to determine a room’s temperature and other characteristics and relay that information to other smart home devices.
Apple also mentioned, by the way, that the four-microphone array in the HomePod mini will, going forward, not only listen for the “Hey Siri” keyphrase for activation (and subsequent verbal interaction), but more broadly listen for various home alarm sounds and send a notification to the owner if they’re identified. Apple has (along with Amazon, Google and others) long been active in developing the Matter and related Thread industry standards for interoperable “smart home” functions, which had their “coming out” party at this year’s CES subsequent to last fall’s unveiling. As someone who’s long grappled with various proprietary, feature-deficient, and otherwise under-delivering technologies and products, Matter and Thread are long in coming.
Nearing 2,500 words, I’m going to wrap up before my associate editor partner wraps a HomePod mini power cord around my neck! “Sound off” with your thoughts in the comments.
Brian Dipert is the Editor-in-Chief of the Edge AI and Vision Alliance, and a Senior Analyst at BDTI and Editor-in-Chief of InsideDSP, the company’s online newsletter.