How I fixed my Lego Mindstorms NXT Robot - flickering screen no more!

Here is what the flickering screen looks like

Best Price on the Lego Mindstorms NXT Robot

Solving a flickering screen problem on the Lego NXT Robotics System

I've been teaching robotics using the Lego Mindstorms NXT (and previously the RCX ) robotics system for a number of years now. I usually have four NXTs and multiple storage bins going at anyone class. Typically the classes and summer camps are sold out with a maximum of eight kids, so they team up two to a Mindstorms robot.

Most of the time everything goes well but occasionally the kids drop the robots. The Lego Mindstorms NXTs, which are the brains of the system are rather rugged but they are made of circuit boards and the LCD screen is glass so they can break if really abused. I had one kid who seemed to be having problems at home take his frustration out on one of my Mindstorms NXTs - he purposely slammed it to the floor. The NXT didn't totally break but the screen started to flicker. You still could program it and run it but you couldn't always see what was going on, on the LCD screen of the NXT.

I tried upgrading the firmware and other software solutions and eventually gave up and bought another unit. Its tough when you are basically volunteering your time to have to spend all of the money you do earn on equipment.

Here is the fix that worked for me. No promises that it will work for you and I suggest running through all of the resetting and firmware upgrade fixes before attempting any soldering on your unit.

The Mindstorms NXT Fix - Step by Step

  1. Remove casing (remove batteries and four screws in battery compartment)
  2. Remove two daughter board screws
  3. Separate daughter board from main circuit board
  4. Separate daughter board (green) from white support board
  5. Pull daughter board away from LCD and flip up to expose surface mount capacitors
  6. Touch soldering iron to solder joints to resolder
  7. Reassemble and test

In my own experience I had to redo this procedure a few times. I also touched C4 in addition to C1 - C3. Good luck! Photos below plus a step by step video from Javapda on how to solve the flickering screen problem on the Lego Mindstorms NXT.

Now keep in mind there are not guarantee that this will work or that you will do it properly or not damage the NXT permanently. But if you have a non-working NXT this method is worth the risk before buying a new one. Lego should really have issued a recall on this product in my opinion as it is a common problem and should be considered a faulty product. I had an RCA TV once that had a similar weak soldering joint that caused thousands of TVs to fail. RCA to their credit issued a recall so customers could take their TVs in to repair shops to get fixed.

If you have any doubts about your ability to solder small parts, you might consider taking the NXT unit to a local electronics repair shop with these instructions. Maybe for a charge of 15 minutes of work they will be able to revive your NXT.

Copyright Edward M. Fielding

Lego Mindstorms NXT repair step by step

Take out the batteries and remove the four black screws.
Take out the batteries and remove the four black screws.
Unscrew the two LCD screws and then disconnect the daughter board by pulling the plug.
Unscrew the two LCD screws and then disconnect the daughter board by pulling the plug.
Lift up on the daughter board and pull forward to get at the capacitors.
Lift up on the daughter board and pull forward to get at the capacitors.
Flip up the daughter board to see the surface mounted capacitors.  The solder joints are weak.  Touching a soldering iron to them fixes them in most cases.  It might take a few tries.
Flip up the daughter board to see the surface mounted capacitors. The solder joints are weak. Touching a soldering iron to them fixes them in most cases. It might take a few tries.
It works!  No more flickering NXT screen!
It works! No more flickering NXT screen!

Here is the video guide to fixing the Lego Mindstorms NXT flickering screen problem - thanks to Javapda!

From one of my robotics classes at the AVA in Lebanon, NH

Mindstorms NXT - Leprechaun Trap

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Comments 11 comments

anonymos 5 years ago

Thank you for providing this video. I thought I would have to buy another $130 NXT!


peanutroaster profile image

peanutroaster 5 years ago from New England Author

I'm glad I could help save another NXT.


Tomasz Lew 5 years ago

Thank you, my son had this kind of problem. I made all procedures showed on video and I fixed problem, but the next day everything came back NXT display anything. I wonder that I damaged or reheat C1, C2 or C3, but I can't find the capacity of that parts, could you help me please?

My mail: tomasz_lew@o2.pl


ekinnear 5 years ago

It worked for me, but only after a few tries. Thanks!


peanutroaster profile image

peanutroaster 5 years ago from New England Author

ekinnear - It took me a few times also. Probably because we used caution as not to cook the parts. Good job!


Warren 5 years ago

It has been widely acknowledged that resoldering the capacitors has nothing to do with the problem- The problem is in the ribbon cable and it's attach point to the PCB- this cable lifts up and some signals become disconnected. Heating and flexing the board temporarily fixes the problem, but it may require multiple attempts and almost always comes back. The larger capacitors are 1uF.


peanutroaster profile image

peanutroaster 5 years ago from New England Author

Warren - what do you mean "widely acknowledged"? Do you have a good source of information about this?


peanutroaster profile image

peanutroaster 5 years ago from New England Author

BTW - My FLL team, the Pepper Panda People from Hanover, NH made it to states this year! On to Manchester...


WT 4 years ago

I don't know what happened, but when I tried to fix my brick I accidently removed the component labeled C3 with the sodering iron. Then, thinking I broke it, started reassembling it. As I put the case back on I bumped the power button and it turned on. I am shocked and would be grateful if anyone had an explanation.


Mack Crawford 4 years ago

Just so you know, Lego will replace these parts for free as long as the problem is their fault (which it is in this case). They might want the old one back though (but might not, they never asked me to return mine) so if you're going to mess with it you should probably make sure they don't want it returned. They might not accept it if its been taken apart to try and fix it.


GetitScene profile image

GetitScene 3 years ago from The High Seas

Great hub.

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