Repairing a Lego NXT display screen

The Lego NXT brick has a common fault with its display screen - it goes blank and stops working altogether, or it develops stripes and/or flickering, where you can sometimes make out what's supposed to be being display, and sometimes you can't.

The brick itself still works fine - you can program it over USB or Bluetooth, you can turn it on (and provided you can remember where you are in the menu system, you can turn it off again), and it will still run programs (which is easiest if you talk to it over Bluetooth from a PC instead of trying to fiddle around invisible menus with no audio feedback either).

If you do a web search for this problem, you'll find out that it's basically all to do with the flexible cable used to connect the LCD to the PCB. After some years (and remember that the NXT was introduced in 2006 and replaced by the EV3 in 2013, so these bricks are quite old by now) the cable either (partially) detaches from the PCB, or loses conductivity somewhere along its length - it's basically just a strip of plastic with carbon tracks to carry the signals from PCB to LCD.

You'll also find quite a variety of proposed solutions. These range from simply pressing the cable back against the PCB (and putting something there to maintain the pressure), via replacing/resoldering some capacitors, to replacing the cable with wires (which is easy to do at the PCB end, since there are gold pads you can solder onto, but not so easy at the LCD end, since this just has transparent conductive tracks on the surface of the glass - which of course you cannot solder onto).

I have a slightly alternative idea - replacing the wires, but connecting them (electrically) to the LCD by a different means.

I'll document it here once I've tried it out and taken some photos.

Since having this idea, I found out that I'm not the first one to document this approach.

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