Broken NXTs, Looking For More Info

[letsbuild]

Hello everyone!

My school has many NXTs, both first generation and 2.0, and some EV3s. Since we got them, we've had Bricks failing, at least one a year. All the robots have been treated properly.

Below is a picture of most of our broken NXTs, of which we have 10 in total. The main problem, present in 8 of them, is an LCD screen that fails to display anything. The Brick still makes sound and responds to button presses, but we cannot see what is going on.

They are all from 2006. I don't know if that is helpful.

I am just looking for more information, maybe even a way to fix them.

Thank you!

[skppo]

My NXT failed the same way. This rather common issue is caused by the ribbon cable between the pcb and the display that loses contact over time.

It seems like a design failure.

Here is a video that I found that has one way to solve the issue. I haven't tried to fix it myself, but this at least shows the exact part that is the problem.

 

[kieran]

From memory, there are also some small surface mount capacitors that are next to the screen connection that cause issues with dry joints 

[Toastie]

Wow, this is a very nice video! And it will sure work that way.

I believe the correct bending though requires some skills and experience in finding the appropriate length and angles. Nevertheless, very elegant solution!

When the contacts are the issue though, I'd first give chemistry a little try. There are various "sprays" for use in electronics that are available to deal with exactly this kind of issue. I have never done this on the NXT but may work here as well, as it does on other circuity, for example on RCX and Scout PBricks:

Remove everything as shown - but then inspect the flat cable/PCB connection rather than firing-up the solder iron right away. Then use a cleaning spray and jiggle the cable a bit. Then apply very carefully contact spray. Remove any excess. That should work - should as in should.

This would be even better: From the video I can't tell whether or not the cable may be removed easily from the PCB - it should though. If that is the case then carefully remove it, clean everything with cleaning spray, apply a minute amount of contact spray, put it back on. I would also clean of the contact surfaces of the rubber keys and the corresponding contacts on the PCB as they will be the next pieces to begin to fail (indicated by the increasing pressure you need to get the key working)      

Good luck!

Best regards

Thorsten

[ifilin]

2 years ago (may 2016) I've bought sealed set 9797. Display of main brick didn't work. I've made video about that issue and sent to Lego support.

They sent to me new main brick with working display.

[Carsten Svendsen]

I too have two NXT's where the display doesn't work. I managed to make one of them work for a few weeks by opening the unit and putting a heat gun to it.