Teardown: Inside a DSL gateway

Back in June 2014, I mentioned that a new DSL modem-plus-router my then-fiancée had received, a CenturyLink-branded ZyXEL PK5001Z, was covered by a clear plastic protective sheet that also happened to obscure the air vents. Had I not seen and removed it prior to plugging it in, thermal effects likely would have prematurely ended the device's operating life.

My then-fiancée is my now-wife, and our new residence is Comcast cable broadband-serviced. Anyway, I'm not a big fan of integrated gateways, regardless of whether they're cable or DSL-intended. So perhaps obviously, this particular unit became a prime teardown candidate.

Removing two screws and gently unsnapping a few front-panel plastic clips enabled easy disassembly. Here's what the upper half of the enclosure looks like after removal (I replaced the screws in the second shot, to show you where they came from):

And here's an underside shot, with all unique-identification details intentionally blotted out (the paint splatter was caused by a distracted sprayer pre-home sale):

Flip the bottom half over, and the system PCB comes into view:

A PCB closeup enables easier IC discernment:

Here's an even closer-proximity view of the critical digital bits:

In the bottom left quadrant is the Wi-Fi subsystem, based on a Ralink (now MediaTek) RT5362F Wireless Ethernet controller. To its right is a ProMOS V58C2512164 512 Mbit (4 banks × 8Mbit × 16) DDR SDRAM. In the center of the PCB are a Samsung K9F1G08U0D 1 Gbit NAND flash memory and, to its right, the system's “brains” in the form of a Lantiq PSB 50810 EL “XWAY ARX18 ADSL2+ CPE Solution for IAD and Multi-Service Gateway Applications” (to quote from the manufacturer's website). Finally, above them you'll find a Realtek RTL8306M 6-port Fast Ethernet controller, supporting the gateway's integrated four-port switch.

The ZyXEL PK5001Z integrates a 2.4 GHz 802.11n access point, “with 5 dBi antennas (2T × 2R), which provides the ultimate solution: improved speed, reduced dead zones, and extended coverage. With data rates of up to 300 Mbps, the PK5001Z provides stable and reliable wireless connections for high-speed data and multimedia delivery” (again quoting from the manufacturer's website). As such, there are two antennas, one on either side:

Flip the PCB over, and par for the course with devices like this, you'll find … nothing, save for solder points and traces:

I'll close with a closeup of the wall wart's spec sticker:

Fortunately, I seem to have been able to re-assemble the gateway without doing any permanent damage to it. I'll hold onto it in case for some reason we decide to switch back to DSL, since Suddenlink also serves our new neighborhood. For now, as always, I welcome your comments.

Also see:

• 7 ways to shake broadband provider fiscal chains
• Beating the heat: ZyXEL and CenturyLink are in the hot seat