Take Apart a Netgear Nighthawk CAX80 Cable Modem Wi-Fi Router
It's a quiet Friday afternoon and this broken wireless router was just sitting there. Let's see what's inside!
This Netgear Nighthawk CAX80 cable modem is made to replace the modem you would rent from your cable internet provider. This one stopped working after about 3 years of dutiful service as a cable interface, internet router, and wi-fi access point.
Popping off the cover required undoing a secret hidden screw behind the display panel. Then with a snap, all of it's goodies were revealed.
The first thing to notice is the deep-finned aluminum heat seaks. They are all over! I suppose the Broadcom processor is calculating continously. The wireless radios are always on. And the cable transceiver requires high power to stay connected to the cable company 24/7.
Before removing the heatsinks, this Netgear Patent Pending antenna caught my eye. What is this for? Bluetooth maybe? The initial setup asks you to use the Nightawk app on your smartphone. Maybe this is how it links before being connected to the internet.
Next let's look at these four funky antennas. They appear to be installed all higgledy-piggledy, off-kilter, and random. But the arrangment allows for multiple signal patterns from various angles which gives better wi-fi coverage overall. The shape of the antennas also adds to its every-which-way multi-frequency connectivity.
The main processor is a Broadcomm BCM3390 system-on-a-chip made for the DOCSIS 3.1 cable communications protocol. It will also run all of the router features needed to be a wireless gateway. Netgear uses this chip to run their proprietary Nighthawk firmware.
Here is the main board with all the heatsinks and steel coverplates removed. The top of the image is where the reset button, LED on-off switch, ethernet jacks, cable connector, USB 3.1 port, and power plug are located. The LED display lights across the bottom shows status and activity.
The reverse side of the board is also interesting! I am surprised by how much documentation is printed right onto the PCB.
Every capacitor, resistor and component is labeled. And where the label doesn't fit because the components are too close together, they did these mini map call-out sections. Look for the area marked B and find its corresponding layout map B. So cool! You can see more of these closeups in the gallery below.
Here is a closeup of the antenna section. The copper rectangle pads are probably heatsinks for the antenna transmitter chips on the front side of the PCB. Each pad was connected to thermal tape that also stuck to the heatsink. There are five antenna connectors. Four wi-fi antennas and then ANT5 which was attached to the patent-pending antenna. Interesting that ANT5 does not have an associated pair of chips on the front side of the board like the four wi-fi connections do.
This model is decades more sophisticated from the early wi-fi days of having one dipole antenna, one network jack, one function: CONNECT. I wonder what things will look like decades from now. A single quantum chip and holographic component labels?
Check out the gallery of all the photos here: