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USB-C charger teardown

Back in March, EDN published my teardown of a 30W USB-C output gallium nitride (GaN) transistor-based charger from a company called VOLTME. At the time, I told you, and I even showed you:

that I’d also recently acquired a conventional (non-GaN) 30W USB-C charger, this an Insignia (Best Buy’s store brand), which I’d also be dissecting shortly. That time is now.

The VOLTME charger, again, has dimensions of 1.2×1.3×1.2 inches, translating to around 1.9 cubic inches of volume, and weighs 1.5 ounces. Today’s victim, the Insignia, is only a bit larger, 1.43×1.33×1.33 inches (~2.5 cubic inches); I can’t find a weight spec for it on Best Buy’s site.

Back in March, I’d also showed you comparative images of the Insignia charger and an older Aukey 27W one, also conventional in design, which I’d purchased in mid-June 2019 and which finds daily use in recharging my 11” iPad Pro (along with, more recently, my new-to-me M1 MacBook Air…but that’s another story for another time…). Here they are again:

The Aukey device, with model # PA-Y8, has dimensions of 2.17×1.97×1.10 inches (~4.7 cubic inches) and weighs 2.57 ounces. It cost me $17.59 (plus tax), promotion priced. Compare that against the earlier-documented dimensions of the two newer devices. Now consider that the more modern units cost me only $9.99 (VOLTME, purchased in early January) and $10.99 (Insignia, purchased in early February), in both cases again on sale at the time, and plus tax. Half (or less) the volume, and around half the price, after around four years of evolution. Progress!

Now for some standalone shots of our patient. Here it is back in February, still packaged:

Here’s what’s inside, as usual accompanied by a 0.75″ (19.1 mm) diameter U.S. penny for size comparison purposes:

Now for some standalone shots. Front:

Left side:

Back, with the AC plug prongs both retracted and extended:

Right side:

Top, again with the AC plug prongs both retracted and extended:

And finally, the comparatively boring bottom:

Now it’s time for the $10,000 question: how to get inside? The entry points with products like these are usually obvious; there’s typically a seam around the edge of the front panel, as well as the back (which is how I got inside the VOLTME unit). But for obvious high-voltage safety reasons, it’s rarely at all easy to get through those seams; they’re quite sturdy. That was certainly the case here: I started out with the front panel using the combination of a box cutter and a small flat-head screwdriver acting as a chisel, but didn’t get far:

I then turned to my heat gun in the ultimately-shattered aspiration to melt the glue holding the front panel in place:

Instead, I ended up melting a good portion (but not the entirety) of the front panel off:

But the insides remained stubbornly stuck in place, due in no small part to all the grey thermal paste that you can see in this initial glimpse (not to mention all the remaining bits of the front panel that remained stubbornly glued in place):

I then tried ejecting the insides from the case by pushing on the extended AC prongs. No dice. Wielding my implements of destruction on the back panel didn’t do anything, either:

Eventually, I brute-forced my way inside, putting the unit in a vise and applying a hacksaw to it:

Here’s what the “guts” look like, now case-unencumbered but still thermal paste-swathed.


Left side:

Back (no different than the previous perspective, but hold that thought):

Right side:


And much-more-interesting-than-before bottom:

Re my earlier “hold that thought” comment, and as keen-eyed readers may have deduced from the previous “top” view, it turns out that the “guts” comprise two different assemblages, press-fit together (but, in the previous “top view”, moved slightly out of alignment during the case-cutting and “guts”-removal steps). One encompasses the AC prongs, along with a spring-and-latch assembly of some sort, presumably; I couldn’t figure out how to get inside the black-and-white box. The other comprises the bulk (entirety?) of the electronics. You can see on the top edge of the latter assembly’s top view the two PCB contacts that mate with clips on the former:

Here are some more views of the AC prong assembly:

And a closer peek at the top of the main assembly standalone, minus its prior mate:

I realized in retrospect, while writing this piece, that I hadn’t taken another photo of the back of the main assembly at this point. Trust me when I attempt to reassure you that the visage was unmemorable, essentially nothing but a big blob of grey thermal paste, to (among other things) stick the two assemblies together. You’ll see what it looked like after paste removal shortly.

Speaking of which, it’s now time for an isopropyl alcohol bath, reminiscent of last time (this time I used a shot glass instead):

followed by tedious chip-off of the paste using the combo of a fingernail and toothpick. Then back in the shot glass for another soak…wash, rinse and repeat multiple times…

And finally the deed was done, at least to the degree that my patience afforded. Front first, striving to keep the same cadence (and orientation) as in prior photo sequences:

Last time I found a small black piece of plastic that, when removed, exposed more circuitry to view. I found one again this time: presumably their functions aren’t simply aesthetic but also protective. See it in the upper left, extending across the top left edge of the transformer?

Here’s what the front looks like when I slip it off:

The rationale for the plastic piece becomes more obvious when you look at the left side. Here it is temporarily put back in place:

Now removed and exposing several more passives to view, three capacitors and two resistors, to be precise (the piece slides into that groove in the PCB you may have already noticed):

Now here’s that shot of the prong-less back side that I previously promised; the green toroidal coil inductor and two big brown capacitors were completely immersed in grey goo previously:

Right side:


And last but not least, bottom:

Fini et terminé! As I’ve confessed plenty of times in the past, “1”s and “0”s are my specialty, not power electronics. As such, instead of attempting further analysis myself (predictably embarrassing myself in the process), I’ll now turn the microphone/pen/keyboard/pick-your-favorite-analogy over to all of you for your thoughts in the comments!

I’ll hold onto the “guts” for a while so that I can respond to any incoming component identity or other similar questions that folks may have, for which my magnifying glass perspectives may be illuminating. Just don’t ask me to reconnect the two halves, plug the unified assemblage into an AC outlet and see if it still works…trust me, I’ve thought of but successfully ignored that temptation plenty of times already!

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.

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