8x8x8 Cube Unreliable

[RatCatcher]

Hi all - I'm in the process of building the 8x8x8 Cube but I've noticed the cube frequently doesn't power up successfully.

As per the build instructions I'm testing each 8x8 LED layer by connecting it to the board and applying +ve to each anode row in turn. However when I apply power the board (from either the con1 power connector, serial header or the ICSP header) it only seems to successfully power up once every 20 or so cycles.

The large LED feet do glow dimly but don't move on to the bright flash and then steady bright sequence. None of the LEDs in the grid illuminate while the large ones are dim. The reset button has no effect and removing power has no effect.

I have noticed that leaving the board powered down for an hour or so does seem to reset it but after a couple of successful cycles it fails to power properly again.

I've checked all of the solder joints and tried different PSU's.

Any help gratefully received!

[andrew]

However when I apply power the board (from either the con1 power connector, serial header or the ICSP header) it only seems to successfully power up once every 20 or so cycles.

The large LED feet do glow dimly but don't move on to the bright flash and then steady bright sequence.

It sounds like the ATMega328 microcontroller (U2) is not booting for some reason. The base LEDs glowing dimly is also an indicator of this. As it does sound like it’s running on occasion I’d be more inclined to suspect a bad connection or a problem with one of the components connected to this chip rather than the microcontroller itself. Can you try the following things…

1) Try carefully removing and reinserting the microcontroller U1

2) Although you have already checked the soldering, can you give the pads of these components a double check: U2, R1, C13, C14, and X1. Try reheating the pads with your soldering iron if possible

3) The crystal (X1) which is used by the microcontroller for timing is a very sensitive component and sometimes solder or flux can get under the pads and stop it from working properly. If you can, try lifting the crystal off the PCB slightly. You can do this by heating each pad at a time and carefully lifting that side of the crystal slightly whilst that pad is heated.

Edit:
4) Could you also check that none of the components are getting hot to the touch


If you have no luck with the above can you let me know if you have a multimeter?

[RatCatcher]

Thanks Andrew - will go through these steps and report back.

All the best