Teardown: Ethernet and EMP take out TV tuner

-November 12, 2014

So far in this series, I've (in a blog post) described the lightning bolt near-hit that my Rocky Mountain residence experienced in mid-August and dissected two of its casualties, those being five- and eight-port Gigabit Ethernet switches. This time, the third victim goes "under the knife." It's SiliconDust's HDHomeRun Prime networked CableCARD adapter, which embeds three QAM tuners and is intended for mating to a companion PC-as-Windows Media Center server.





The top and bottom halves of the plastic case are held together by a few diminutive torx screws.



Their head type and dimension aren't mainstream, but you didn't think I'd let that stop me, did you? Removing them enables me to disassemble the enclosure, exposing the PCB to full view. Here's its topside:



The first thing you might notice is the system SoC, located near the PCB center, whose identity is obscured by a heat sink. I wasn't able to find a FCC ID stamp anywhere on the PCB, which might enable me to documentation-discern the SoC's part number and supplier, but once again WikiDevi came through for me. The chip is Ubicom's IP7150U communications and media processor; the company was acquired in early 2012 and I can't find any mention of the SoC on new owner Qualcomm's website. Here's an archive of the relevant product page.

To the left of the IP7150U you'll find two semiconductor memories; a Macronix MX25L1655D 16 Mbit serial interface flash memory (presumably intended to store system boot code and other software), and a Hynix H5PS5162FFR 64 Mbit DDR2 SDRAM. To the left on the photo is the CableCARD socket; to the right is the three-tuner "can." Between them, at the top, are (left-to-right) the "wall wart" power connector, Ethernet connector, and USB-reminiscent SDV (switched digital video) connector. And at the bottom, are the five front-panel LEDs. The one on the left is normally green; it's red when the HDHomeRun Prime can't go online. The one to its right is also normally green; it flashes when the CableCARD is present but not ready, and is dark when the CableCARD is not present or not detected. And the remaining three on the right, when green-lit, signify a respective tuner in use.

In my particular case, after the lightning strike, the CableCARD-associated LED remained green, but the LAN-associated LED went red and remained in that state no matter what I did. That fact leads me to the remaining notable IC on the PCB, a Realtek RTL8211CL single-port Ethernet controller. If you've read my previous writeups on this subject, you already know that I don't believe a premises power surge was behind the devices' failures. Instead, I think that the EMP (electromagnetic pulse) generated by the lightning bolt coupled to Ethernet cable, acting as an antenna, and zapped relevant ICs inside the devices via that path.

The HDHomeRun Prime's condition supports this theory, at least to me. As far as I can tell, it's otherwise still fully functional. But it refuses to go online, suggesting that its Ethernet subsystem has expired. The HDHomeRun Prime had been directly connected to the router via a short span of Ethernet cable, coiled together like a crude inductor and sticking up in the air. In came the EMP, and … zap (although, unlike with the D-Link GO-SW-8GE eight-port GbE switch, there's no visible evidence of the Realtek controller's demise). Why the router on the other end of the Ethernet cable coil didn't experience a similar fate is anyone's guess.

In the interest of completeness, I'll close with a close-up of the unmemorable PCB underside:



And some rare praise for Comcast. I happened to have a spare HDHomeRun Prime lying around, but when I plugged the CableCARD into it, I found that I was only able to receive a very small and basic set of channels. And, when I accessed the HDHomeRun Prime's built-in Web server status screens, they indicated that the associated CableCARD needed to be reactivated. A quick call to Comcast's CableCARD-tailored toll-free phone number, after an even quicker preliminary online chat with Comcast support, sorted things out straightaway. The new HDHomeRun Prime, obvious to me in retrospect, had a different Host ID than its precursor, but Comcast's database still contained the old Host ID information. Purging the old Host ID, adding the new one, and remote-resetting the CableCARD had me going again in no time.

This teardown is part of a series on equipment damaged by a lightning strike. Read the rest of the series here:

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