Office & commsYou will see this often

Router or modem

Also called Wi-Fi router, cable modem, access point.

A small enclosure, a known barrel jack, antennas, and an external brick that is the actual prize. The SoC is not a hobby computer you can repurpose just because it runs Linux in someone else's firmware.

A donor is the dead machine. The parts below are what is still worth removing from it. “Leave it” is a part that is physically in there and should stay in there: too dangerous, too worn, or only useful as part of a repair you are not doing.

What you are looking at

A scrapped machine is a box of parts that failed at different times. The reason it was thrown out is often one bad piece. The motor, the cord, the supply, and the screws are frequently still good. This index says which is which.

Why it is in the trash while the parts are not

The ISP replaced it, or it no longer gets updates. The brick is almost always healthy.

Before you open it

Do this while it is still unplugged, cool, and not leaking. Unplug the brick. There is little stored energy, but it is still mains on the brick side.

Mains voltage

Where the dead machine usually is

Home office — In the house
Junk drawer and cable box — In the house
Office cleanout — Commercial
Move-out week — Curb

The brick migrates to the junk drawer and loses its label in your memory. Write the voltage on it the day you salvage it.

How it comes apart

Screws under the label. Antennas unscrew or are internal pigtails.

Tools: Phillips, Spudger.

Words on this page

mains: Ordinary household wall power. It can kill. Unplug before you open anything that used it, and do not experiment on live wiring.

What to take

The table is the short version. The notes under it describe that part inside this machine, not only the general description.

Parts in this donor
Part	Call	How many	How often	Where to look
Switch-mode wall supply	Prize	1	always	The external brick.
Barrel jack	Worth pulling	1	always	Rear panel.
Antenna pigtail	Worth pulling	1–3	usually	From the board to the antenna.
Enclosure	Worth pulling	1	always	The shell.
Electrolytic capacitor	Bonus	2–4	usually	Near the jack.
Linear regulator	Bonus	1	usually	Near the SoC.
Indicator LED	Bonus	several	always	Front panel.
Pin header and connector	Bonus	1	sometimes	A UART pad group.

Prize

Prize — take this firstSwitch-mode wall supply1 · always
Commonly 9 or 12 V at 1 A class. Read it.
The external brick.
Label voltage, polarity, and measured current capability if you load-test it.
Usually good.

Worth pulling

Worth pullingBarrel jack1 · always
5.5 mm class. Confirm the bore.
Rear panel.
Keep the jack with the brick.
Loose sleeves are a reject.
Worth pullingAntenna pigtail1–3 · usually
U.FL to a small dipole.
From the board to the antenna.
Pop the connector straight.
Good if the center pin is straight.
Worth pullingEnclosure1 · always
A vented plastic box with an antenna hole.
The shell.
Good project size.
Clips break.

Bonus

Bonus, if you are already in thereElectrolytic capacitor2–4 · usually
Input filter caps. If the router rebooted randomly they may be the fault.
Near the jack.
Test before keeping.
Mixed.
Bonus, if you are already in thereLinear regulator1 · usually
Often a 3.3 V SOT-223 regulator.
Near the SoC.
Only if the marking is a part you recognize.
Unknown otherwise.
Bonus, if you are already in thereIndicator LEDseveral · always
Ordinary indicators on a harness.
Front panel.
Keep the light-pipe with them if you want the look.
Good.
Bonus, if you are already in therePin header and connector1 · sometimes
Unlabeled 3.3 V serial, if you already do that kind of work.
A UART pad group.
Do not invent a pinout.
Fine.