Google’s Chromecast with Google TV: Dissecting the HD edition

At the end of a few-months-ago writeup, wherein I successfully reassembled a 4K-version Google Chromecast with Google TV:

that I’d taken apart earlier in the year, I wrote:

In closing, a foreshadowing. As I mentioned in my earlier teardown, written and submitted for publication in mid-March:

“Mine’s one of the original 4K resolution-capable units introduced in September 2020, not the newer (September 2022) and less expensive ($29.99 vs $49.99) albeit “only” 1080p-max “HD” model.”

Well, I subsequently also picked up one of those newer Google Chromecast with Google TV HD (wow, that’s a mouthful!) devices, in late April when Walmart had them on sale for $19.98:

It looks just like its “4K” big brother, doesn’t it? Makes you wonder if the hardware is identical, and Google just differentiates the two devices solely via software, doesn’t it? There’s only one way to find out; it’s in my teardown pile, and I’ve promised Aalyia it’s near the top of the stack. Stay tuned for the “full monty” coming soon; until then, share your thoughts in the comments.

That time is now! Some upfront if-necessary clarification: while the earlier 4K “CGTV” (for short) supported output video resolutions of, per the published tech specs “Up to 4K HDR, 60 FPS”, this version conversely is “only” capable of “Up to 1080p HDR, 60 FPS”. Strictly speaking, leveraging the terminology commonly found with computer monitors, Google maybe should have called it the “FHD” edition, for 1080p (1920×1080 progressive-scan) “full HD”, since 720p (1080×720 pixel progressive-scan) support is all that’s necessary to claim conventional “HD” capabilities. Further to this point, I should also point out that “FHD” (or “4K”, for that matter) doesn’t also require HDR (high dynamic range) or 60 frame-per-second display output capabilities, both of which both of these device variants also support as feature supersets.

The differentiation continues with the devices’ supported audio and video formats. First, here’s the 4K CGTV:

Audio: Dolby Digital, Dolby Digital Plus, and Dolby Atmos via HDMI passthrough
Video: Dolby Vision, HDR10, HDR10+, HLG (Hybrid Log-Gamma)

Now for the “HD” version:

Audio: Dolby Digital, Dolby Digital Plus, and Dolby Atmos via HDMI passthrough
Video: HDR10, HDR10+, HLG (note: no Dolby Vision support in this case)

While the various “4K” version’s A/V enhancements could come solely from different software builds installed on a common hardware foundation, I’ve always suspected that the two versions have unique hardware designs. For one thing, the FCC IDs are different, suggestive of two different hardware platform certifications: A4RGZRNL for the 4K version and A4RG454V for the newer HD version (that said, any Bluetooth, Wi-Fi or other RF broadcast differences between the two products might also result solely from different software builds that selectively enable and tweak various wireless subsystems).

The HD version is also nearly half the price of its 4K sibling; any resultant higher sales volumes might not be enough to counterbalance lower unit profit margin on a common hardware foundation, making a bill-of-materials cost reduction potentially also necessary to hit revenue and profit targets. That all said, why might Google consider basing both product proliferations off a common hardware foundation at all? The advantages here would involve manufacturing line and inventory simplification. Obviously, the end retail packaging for the two versions would need to differ, but they’d be identical right up to the point where final firmware is programmed into a particular device (via the USB-C port, for example) and it’s packaged and shipped either to a retail partner or directly to the customer (for products sold from the online Google Store).

So, which is it in reality: one hardware foundation, or two? Let’s find out. I’m not going to repeat the entire suite of images shown for the 4K device back in May, except selectively to reinforce commonality (or not), so I encourage you to back-reference my earlier writeup for the “full picture” (bad pun intended). But I will as-usual start with some packaging shots post-clear plastic shrink-wrap removal (to preclude annoying camera reflections in the shots). Front (note the “HD” mark in the lower left corner this time):

Left side:

Back:

Right side:

Top:

And bottom, again with varying markings from last time reflective of HD-vs-4K differentiation:

Same contents as last time:

The USB-to-USB C power adapters are the same. 4K version:

And HD version:

As are the remote controls. 4K version:

And HD version:

Now we get to the deviations, specifically the players themselves:

although truth be told, everything looks the same as before (including the ever-present accompanying 0.75″ (19.1 mm) diameter U.S. penny for size comparison purposes)…

until you flip the HD unit over and peer closely at the markings stamped on its backside:

Time to dive inside:

Things still look pretty much the same at this point, save for an altered number and pattern of thermal paste imprints. 4K version:

and HD version:

Remove four screws:

and pop off the topside heat sink/Faraday cage, however, and the uniqueness of the PCB this around this time is unmistakable. 4K version:

and HD version:

The pattern of the inner Faraday Cage rim is different in the upper left corner this time, for one thing. Also look at the four quadrants inside the outer Faraday cage. Last time there were notable ICs in the upper and lower right quadrants; that extra blob of thermal paste on the left side was, as I mentioned at the time, to dissipate heat from an IC on the other side of the PCB. This time, three of the four quadrants (also including the upper left) are large-IC-populated.

Clearly, I’m going to need to remove the entire PCB again to get a full comparative picture. Let’s first clean the paste off the ICs and PCB itself:

Now remove the two additional screws holding the HDMI cable in place and attached to the enclosure shell lower half (although I didn’t bother disconnecting the cable itself from the PCB):

And the PCB-plus-cable combo then pops right out of the remainder of the case:

One more heat sink/Faraday cage to go; no screw removals needed this time:

And after some more thermal paste cleanup courtesy of isopropyl alcohol and elbow grease, here’s how the two versions compare from a PCB backside perspective. 4K version:

and HD version:

The types of ICs—system processor and DRAM—are the same. The specifics are where the variance lies. Last time, the system SoC was Amlogic’s S905 and the DRAM was a Hynix H9HCNNNBKUMLHR-NME 16 Gbit LPDDR4-3733 SDRAM. This time, the system SoC is Amlogic’s newer, lower-end S805X2. And the DRAM? Smaller capacity, slightly slower, and from a different supplier: Nanya Technology’s NT5AD256M16E4-HR 4 Gbit standard DDR4-2666 SDRAM.

Back to the PCB front side for one more comparison. 4K version:

and HD version:

As mentioned earlier, the 4K product design includes only two sizeable ICs on this side of the PCB: a Samsung KLM8G1GETF-B041 8 GByte eMMC flash memory and a Broadcom-then-Cypress Semiconductor-now-Infineon Technologies BCM43598 “single-chip IEEE 802.11 b/g/n MAC/baseband/radio with integrated Bluetooth 5.1 compliance”. The nonvolatile storage chip in the upper right quadrant is unchanged for the HD generation, albeit rotated, but the wireless connectivity is now supplied by a NXP Semiconductors 88W8987 in the bottom right, originally intended by its supplier (per Google’s cache) for automotive applications, interestingly. And that “new” IC in the upper left? It’s another SDRAM, this one from Micron Technology, the MT40A512M16TB-062E (identified by a D8BPK code stamped atop it) 8 Gbit DDR-3200 device.

One DRAM for code execution, and the other for a video-decode buffer? That’s my guess. Let me know your thoughts on this or anything else in the comments! ICs aside, the hardware designs are otherwise largely identical, including (beyond already-mentioned bits) their reset switches, status LEDs and various PCB-embedded antennae. I’ll eventually tackle reassembling this HD device to fully functional “new” condition, as with its 4K sibling, but for now I’ll keep it in pieces so I can answer any other questions you all might have about its insides.

—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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The post Google’s Chromecast with Google TV: Dissecting the HD edition appeared first on EDN.

Google’s Chromecast with Google TV: Dissecting the HD edition

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