Hobby Components 8x8x8 Cube Kit (HCKITS0050)

[Scarebird]

I've dismantled the cube matrix, and gone back to double checking each individual LED assembly, due to the resistance reading I was getting. I checked continuity between the anode/cathode, cathode/cathode and anode/anode on each of the 8 assemblies. As I result I have replaced 7 LEDs that were allowing current to flow in the reverse direction, and then re-checked continuity. Everything as far as the LED matrix goes is now how it should be.

Checking pin 2 on U1 directly to ground gives an initial reading of around 1950 ohms, which slowly drops to 1750 ohms where it remains steady.
Pin 24 on the micro controller to ground shows open circuit, as does this pin to U1 pin 2!!



I will go and reflow Pin 24 and report back.

[Scarebird]

Pin 24 has been re-worked and there is now a connection through to pin 2 on U1. I also re-worked pin 25 as that was looking a bit dodgy in the photo as well. I no longer have a reading from pin 2 U1 to ground, so fingers crossed. All I need do now is reassemble the cube and see how things go.

[Scarebird]

SUCCESS

Difficult to believe that a) I didn't solder that pin correctly to start with and b) missed that it was a poor joint the first time I checked it.

I don't think I am solely to blame though, having identified quite a few LEDs that were passing current in the reverse direction. I must stress that all LEDs were checked to see that they lit up correctly before I started putting the cube together, but that didn't pick up the dud ones.

Andrew, I'd like to say a big thank you for taking the time to read my posts detailing my problems and for then coming back with suggestions which, happily, enabled me to finally get the cube working as it should.

Thank you.

[andrew]

That's great. Knew the layer issue had to be something to do with those pins. Sometimes bad joints can be hard to see without a magnifying glass and good lighting but at least with your helpful information we could quickly pinpoint the problem. Enjoy your cube.

[Cube1]

Hello, when I was testing one of the layers (Step 5), all of the LEDs turned off. Now when I plug it in, the feet light up for a short period, before dimming slowly, and eventually dying completely. What is the likely cause for this?

Any help appreciated, thanks.

[andrew]

Now when I plug it in, the feet light up for a short period, before dimming slowly, and eventually dying completely.

The feet are connected to the 5V supply rail. It is normal for them to be dim for a few seconds after the cube is first powered up but it could also be a sign that something is overloading the 5V supply, or that your power supply is not capable of powering the cube.

Can you first check if any of the components are getting hot to touch - especially the ICs and regulator. If so then disconnect your power supply and let me know which component(s) are getting hot.

Can you also let me know how you are powering the cube?

[Cube1]

Can you first check if any of the components are getting hot to touch - especially the ICs and regulator. If so then disconnect your power supply and let me know which component(s) are getting hot.

Thanks for the quick response, the feet were working fine, and the first 3 layers tested ok. When I was testing the 4th layer I accidentally touched the top of the layer. I thought perhaps this could have shorted something. I was powering it through p1 serial with the USB plugged into my laptop.

[andrew]

When I was testing the 4th layer I accidentally touched the top of the layer. I thought perhaps this could have shorted something.

The actual LED cube is quite forgiving in this way. The only way that I can think of damaging the cube by shorting a layer is if you shorted one of the layer select lines (L1 to L8) to 0V. This could potentially damage IC U3 but if that was the case the chip would be getting hot (I assume none of the components are getting hot?) and I wouldn't expect even the base LEDs to illuminate so I doubt that's the issue.

I think based on the information you have given me it's most likely a lose connection somewhere. The first thing we can do is to figure out if the microcontroller is actually running. Can you power up the cube and after about 10 to 15 seconds the 10mm base LEDs should flash a few times.

Does this happen?

[Cube1]

The only way that I can think of damaging the cube by shorting a layer is if you shorted one of the layer select lines (L1 to L8) to 0V.

Hey Andrew, I think this may have happened. When I plug it in now nothing is happening, but none of the IC's are getting hot either. I've checked all the connections, they seem fine. I think its important to note that I haven't a clue about electronics.

[andrew]

When I plug it in now nothing is happening

I take it that not even the 10mm LEDs are lighting up now either?

I'd still be surprised if it is IC U3 but an easy way to find out is to simply remove it and then plug the cube back in. If U3 is causing then problem then the 10mm LEDs should light up again with it removed. Can you give it a try and let me know if they light up. Be careful when removing the IC as they are a tight fit. If you can find something flat like a screwdriver blade to leaver it out from both ends you should find it a lot easier to get out.

I think its important to note that I haven't a clue about electronics.

No problem, I'll keep this in mind.