Infosec Scribbles

June 5, 2013

How to take apart TG789vn and extract the parts from it

So I recently got a box full of Thomson TG789vn routers with half of them not working properly. Say “Hello” to lightnings hitting the power lines in Estonia. With nothing to lose it was decided to pop one open to see if there is any obvious damage that can be repaired. Surprisingly, there were no guides on the internet on how to open TG789vn without breaking anything, so here is one.

Stuff You Will Need

  • Thomson TG789vn router
  • Phillips screwdriver
  • Flat-blade screwdriver
  • Two hands and a little bit of common sense

Needless to say, before doing any of this you need to turn off your router and unplug everything from it. This will also void your warranty and I will not be held responsible for any damage you may or may not inflict upon your router.

Step 1: Bottom Screws

First, locate the two “legs” at the bottom of your router. There are rubber pads glued to them. Use a knife or a flat screwdriver to take them off and put them aside. Under the pads you will find a screw on each leg. Unscrew those with a Phillips screwdriver.

Bottom screws location

Step 2: Side Clips

Here comes the tricky bit: you will need to push 10 plastic clips on the sides with a thin flat screwdriver. I say tricky because in my case they wouldn’t let go without applying force and bending the case slightly. See the locations of the clips on the picture below.

10 clips for you to hit

Step 3: The Board

Now you need to unscrew the board. There are 3 screws attaching it to the back of the plastic case. Unscrew them with a Phillips screwdriver and you can take the board out. Start by freeing the corners, then gently pull out the side of the board with all the buttons without bending it too much. Now pull the whole thing to the side with the buttons to get the USB ports out.

Once you’ve done that, do not pull the board all the way up. There is a wireless “antenna” on the other side with one end attached to the board and other glued to the top of the case. Pull out the wire from the board connector - you can do this with a flat screwdriver. Now the board is yours to experiment with :)

The screws on the back

What Can I Do With My TG789vn Now?

Replacing the built-in paperclip antenna could be a good start. You can go grab U.FL-to-RPSMA wire from Farnell, drill a hole in the case for it and connect this instead of the original antenna:

Original antenna

With RP-SMA connector you could use any other antenna, like this +5dB one to increase your TG789vn wireless network coverage. If you can solder and want something more extreme, you could make a cantenna. Or maybe the whole point of reading this was to get access to the JTAG interface. Go wild!

Back of the TG789vn board

The front of the TG789vn board