Teardown: Analyzing a zero-cost router

-May 22, 2017

Not impressed with the $10 (after rebate) 2.4 GHz 802.11n access point, network extender and bridge combo device that I recently disassembled for your perusal? Ok, how does a $0 (after rebate) 2.4 GHz 802.11n router strike your fancy? I recently saw it on sale for $5, after a $7.99 coupon-code savings from the original $12.99 price tag. A further $5 rebate dropped the final price to a goose egg ... plus $4.99 for shipping, but who's quibbling?

Granted On Networks' N150R is (as its name implies) "only" a N150-class device ... but then again, most of you won't even achieve those speeds in the 2.4 Ghz band, even on your fancy-schmancy high-end 802.11ac router, since they require the use of a 40 MHz wide channel which precludes simultaneous multi-channel network configurations within your office or home (and un-neighborly squats on neighbors' spectrum, too). And although the user feedback at Amazon, Newegg, and elsewhere suggests that the factory default firmware is fairly unstable, not to mention no longer supported, the N150R can alternatively be flashed with specific versions of open-source DD-WRT, OpenWrt or Gargoyle (enabling, among other things, additional access point and bridge operating mode options), along with firmware from Netgear. Wait ... Netgear? Hold that thought.

I'll start out, as usual, with some box shots:

Inside the box, you'll find the wall wart, along with an Ethernet cable (nice touch), and a smattering of paperwork; the GPL documentation, plus a quick-start guide.

Here's a closeup of the former. Notice the "Netgear Japan" logo in the bottom right corner? Again, hold that thought.

Also in the box, of course, is the router itself:

It's not quite as diminutive as the EDIMAX EW-7438RPn was, but it's still pretty tiny:

Here’s a view of the front side:

On the back, note there are only two LAN ports; they along with the WAN port are also only 10/100 Mbps in speed, not GbE-capable ... but did I mention that the N150R was free?

Top (plenty of passive airflow vents; no fan inside):

And bottom (more vents, plus "feet" to preserve airflow-conducive space between the vents and whatever the router's sitting on):

Here are closeups of the labels on both "feet":

Time to dive in. Removing the single torx head screw shown in the earlier underside shots didn't initially seem to do much; I then switched to prying the halves apart from the top:

The router came apart pretty easily; one side first, then, by un-tabbing the PCB in only two places, the other:

Not much to say about the backside of the PCB; as usual with product like this, it contains little but solder points and passives. The PCB front side, however, is more interesting:

Click to enlarge

In the bottom left quadrant is the Wi-Fi subsystem, dominated by an Atheros (now Qualcomm) AR9285 wireless controller:

Click to enlarge

Below it is the single (N150, remember?) antenna, built into the PCB versus discrete, thereby at least in part explaining the transmission/reception range shortcomings that some customers grumbled about:

Above and to the right of the AR9285 are the H12106DK and H20202DL magnetic transformer modules, both from FPE, that respectively service the LAN and WAN ports:

And on the far right is an ESMT (Elite Semiconductor Memory Technology) M13S2561616A 256 Mbit DDR SDRAM:

But what I know you're all really wondering about is what's underneath the mysterious black passive heat sink to the left of the DRAM:

Once again Google comes through, without need for me to risk permanent damage to the hardware (and with dubious identification end result to boot). According to the OpenWrt website, it's an Atheros (again, now Qualcomm) AR7240 SoC, based on a MIPS 24Kc V7.4 processor core running at 400MHz, and also containing 32 MByes of RAM and 4 MBytes of flash memory.

The OpenWrt webpage also has lots of other interesting information on the N150R, including the locations and functions of its various GPIOs and serial port pins ... and the fact that the hardware design is identical to that of Netgear's WNR612 v2 router, as well as being very similar to that of the Netgear WNR2000 v3 (minus a few LAN ports). Let’s see ... didn't I recently also write about another Netgear foundation-hardware router that could be fooled into firmware-transforming into something else? Ah yes ...

Also see:

Loading comments...

Write a Comment

To comment please Log In