How visibly different (if at all) inside are two generations of smart plugs, and is the more recent device’s comparative connectivity issue due to hardware, software, or a combination of the two?
Back in early December, EDN published my initial write-up in a planned series of posts covering experiences setting up and using devices from TP-Link’s two somewhat-overlapping smart home hardware, software, and service ecosystems, Kasa and Tapo. The first two products I’ve tried out (I’ve since added several more to the stable; stand by for additional details in future blog posts and teardowns) were both Kasa-branded and were also both smart plugs: the HS103, which I subsequently dissected here:
and its more diminutive successor, the EP10:
Newer is not necessarily better
My so-far sample set is small, so conclusions should be accordingly calibrated. That said, I’ve had no issues with any of the multiple HS103 devices I’ve so far activated here at the residence, whether in the initial setup steps or during subsequent usage. The same can’t be said, however, for the EP10. None of the devices I tried in either of the first two four-packs I purchased would successfully setup-connect to my Wi-Fi network. But both devices in the third two-pack worked fine…at least until I subsequently disassembled one of them. Meet today’s teardown candidate, as usual, accompanied by a 0.75″ (19.1 mm) diameter U.S. penny for size comparison purposes:
This particular two-pack was sourced from Amazon’s Resale (formerly Warehouse) sub-site, therefore rationalizing the non-TP-Link sticker stuck to the top of the box:
And since, as I’d mentioned previously, I got the idea to do a comparative teardown between the HS103 and EP10 after sending back for refund the original two four-packs of the latter, I can’t say whether their hardware versions matched this device’s v1.6 ID. v1.0 and v1.8 EP10 designs have also been shipped by the company (all three with multiple firmware releases):
Inside…
and underneath a sliver of literature, along with a bit of protective foam:
is our patient:
whose sibling, I’ve already noted, is in active use:
Chassis compaction and invasion
Some as-usual overview shots to start; the EP10 has dimensions of 2.36 x 1.50 x 1.21 in (60 x 38 x 33 mm) and weighs 0.13 lb (59 g) versus its slightly heftier HS103 predecessor at 2.62 x 1.57 x 1.5 in (66.5 x 40 x 38 mm) and 0.25 lb (113 g):
The LED-augmented on/off, pairing and reset switch is on the left side this time:
Theoretically, at least, the visible presence of a screw head implies a potentially simpler disassembly process as compared to the HS103 of the past. We shall see…
Once again, there’s a seam-inclusive topside, suggestive of the pathway inside:
And, last but not least, the bottom-side stamped specification suite, including the always-insightful FCC ID (2AXJ4EP10):
Speaking of pathways inside, let’s take the first step in the journey, shall we?
I wish I could say the two halves of the case then separated straightaway…but that’d be a lie:
Still, the mission was eventually accomplished, this time with an added bonus: no blood loss!
This YouTuber’s video (which, although it claims to be of an HS103, is actually of an EP10; note the switch location, along with glimpses of the bottom-side markings) bolsters my opinion as to the device’s lingering disassembly difficulty. Alas, I didn’t come across it until afterwards:
Comparatively boring front half first:
including a closeup of the left-side mechanical switch’s translucent insides:
Hardware commonality and variation
Now for the (rear) half I suspect you all mostly care about:
The relay on the right side is, at least in my v1.6 hardware version of the design, a Hongfa HF32FV-16, the exact same component I found a month back in my HS103 teardown:
However, the one in the video I just showed you, complete with a convenient “v1.8” hardware version sticker atop it, is blue in color, therefore presumably from a different manufacturer. As is the one shown in the FCC certification internal photos, which is sticker-less, but I’m assuming it references the initial v1.0 hardware design. And now for the other end, containing the digital and RF (control and wireless communications) sections, of which I’m most interested, both in an absolute sense and functionally relative to the HS103 predecessor:
Once again, there’s the on/off, pairing, and reset switch, this time right next to the LED, and with both now surrounded by the previously encountered LED-only light leak-preventing foam. The embedded antenna runs along the PCB’s right edge. And the “brains” of the operation at the end of the antenna are seemingly also the same as in the HS103: Realtek’s RTL8710, which, as I noted before, supports a complete TCP/IP “stack” and integrates a 166 MHz Arm Cortex M3 processor core, 512 Kbytes of RAM, and 1 Mbyte of flash memory. The only differences, perhaps reflective of a silicon revision, are in the IC’s bottom two marking lines. The IC in the HS103 says:
08F01H3
G038A2
while the Realtek RTL87210 in the EP10 design is marked as follows for the 2nd and 3rd lines:
08EL0C1
G031A2
The rest of the story
Alas, and as with the HS103 precursor, I was unsuccessful in my attempt to free the EP10’s PCB from the rear-half case within which it was ensconced. I’ll alternatively attempt to pacify your curiosity by first pointing out that a scattering-of-passive PCB backside image is included in the FCC certification internal photo set. And I’ll also point you toward another video, this one also showing both PCB sides but also more broadly of interest to me (and you as well, I suspect):
I found it within a Reddit post I stumbled across while doing my initial research. The OP (original poster, for those of you not yet familiar with frequently used Reddit verbiage) had an EP10 whose relay had developed perpetually clicking behavior. Turns out one of the “can” capacitors on the board had gone bad; replacing it restored normal functionality (not to mention ending the din). Note that the relay in the version of the hardware shown in this video (which I think also says v1.8, although the video-frame images aren’t clear) is also blue in color.
(Not-) working theories
This internal information is all well and good, I hope you agree, but it still doesn’t answer my fundamental question: why was I successful in using only a subset of the EP10s I tried setting up? I’ll first reiterate something I said in my initial December 2025 coverage:
I wondered if these particular smart plugs, which, like their seemingly more reliable HS103 precursors, are 2.4 GHz Wi-Fi-only, were somehow getting confused by one or more of the several relatively unique quirks of my Google Nest Wifi wireless network:
- The 2.4 GHz and 5 GHz Wi-Fi SSIDs broadcast by any node are the same name, and
- Being a mesh configuration, all nodes (both stronger-signal nearby and weaker, more distant, to which clients sometimes connect instead) also have the exact same SSID.
If I was right, the issue might have been caused by an EP10 software shortcoming, which a newer version of the firmware could conceivably resolve. But this leads to a chicken-and-egg situation. Downloading and installing the latest firmware to the device requires that I first connect the EP10 to TP-Link’s “cloud” firmware repository via my smartphone intermediary. But absent a sufficiently functional initial firmware version, I can’t get the device online in the first place. To wit, note that the TP-Link devices’ lack of Bluetooth support precludes using this alternative wireless communications interface to get them updated; it’s Wi-Fi or nothing.
A fundamental hardware limitation is also a possibility, of course. Via both documented and pictorial evidence, I’m aware (as, now, are you as well) of at least three different hardware versions of the EP10. For that matter, TP-Link’s website currently lists six different hardware versions of the HS103 “in the wild”, ranging from v1.0 to v5.8. All five of the HS103s currently active in my home are v5 units, the Kasa app conveniently tells me via the Device Info screen in each device’s advanced settings. Again, the sample sizes are small and therefore statistically suspect: did I just get lucky with the HS103s, and unlucky with the first two batches of EP10s?
With that, I’ll wrap up and refer you to the comments section below for any answers you might be willing to publicly posit for my closing questions, and/or any other thoughts you might have! Stay tuned, as I alluded to earlier both in this post and a prior one in the series, for additional teardowns to come of products from both TP-Link’s Kasa and Tapo smart plug families, along with other, potentially even more interesting, smart home ecosystem devices.
—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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