Hobby Components 8x8x8 Cube Kit (HCKITS0050)

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Ramshackle
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Joined: Tue Feb 19, 2019 7:36 pm

Re: Hobby Components 8x8x8 Cube Kit (HCKITS0050)

Post by Ramshackle » Wed Feb 27, 2019 11:58 am

Hi, just completed the cube... and appears to be working fine, well done the designer and team who made it easy to follow when putting together, can I just add a few comments, not criticisms by any means!

Would it have been a good idea to include a phone style socket on board when using a standard phone charger to power the cube? The pin and plug idea is easily pulled out. (I noticed an Image somewhere on here with exactly that arrangement) Or is it a soldering issue with something so small?

When building the grids I meticulously tested every led before assembly and after when each grid was finished to eliminate ‘dead pixel’ syndrome, trust me it’s worth the effort when fault finding... would it be possible to add a sequence in ‘modes’ to light ALL leds at once? This will kill two birds with one stone, if you know your leds work at assembly, any grids or portions of not work must be due to an error on the board? - just an idea.

Using usb as the power source I have found the cube to be quite ‘picky’ about the type used (all mine are genuine power units from current or older phones I have owned but none are less than at least 1.2 to 2amp plus) on at least 1 Samsung supply and 1 apple ipad supply the cube does not work unless you hold your hand near the board... almost like magic it starts to work! Power supply noise issue? More filtering needed on the board, or should I be using the power socket on the board....

Finally, possibly an issue, watching the video of the cube working it looks a lot smoother going through the modes, I seem to be getting odd leds that light up where they shouldn’t like in the ‘waves’ mode, 3 or 4 get left alight when moving up and down... odd pixels lag behind on some of the other modes as well... any thoughts?

And finally.. when is the R.G.B morphing colour version coming out.... :D

Cheers guys

andrew
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Re: Hobby Components 8x8x8 Cube Kit (HCKITS0050)

Post by andrew » Thu Feb 28, 2019 9:44 am

Would it have been a good idea to include a phone style socket on board when using a standard phone charger to power the cube? The pin and plug idea is easily pulled out. (I noticed an Image somewhere on here with exactly that arrangement) Or is it a soldering issue with something so small?
This would have been the most convenient way to power it but as you have alluded to above, microUSB sockets only come in surface mount form and as we have discovered in the past, most customers that these kits are aimed at don't have the sufficient equipment or soldering skills to solder surface mount components. That's why all our kits aimed at the beginner to intermediate level only use through-hole components.

We are however looking into adding a new DC socket and USB cable instead of the serial cable we currently supply as it seems that the majority of customers that buy this kit are not bothered about reprogramming it and a USB to DC cable would be more robust.

would it be possible to add a sequence in ‘modes’ to light ALL leds at once?
Yes we've already had this idea. The plan is to update the firmware so that it can be placed into a test mode by holding the mode button down whilst powering up the cube.

Using usb as the power source I have found the cube to be quite ‘picky’ about the type used (all mine are genuine power units from current or older phones I have owned but none are less than at least 1.2 to 2amp plus) on at least 1 Samsung supply and 1 apple ipad supply the cube does not work unless you hold your hand near the board... almost like magic it starts to work! Power supply noise issue? More filtering needed on the board, or should I be using the power socket on the board....
I've not actually seen this issue and making it work by touching the board is a weird one. It could suggest a grounding issue but as you said maybe some USB chargers are just too noisy. I'll try and get hold of some different types to replicate the issue.

Finally, possibly an issue, watching the video of the cube working it looks a lot smoother going through the modes, I seem to be getting odd leds that light up where they shouldn’t like in the ‘waves’ mode, 3 or 4 get left alight when moving up and down... odd pixels lag behind on some of the other modes as well... any thoughts?

That's defiantly not normal behaviour, it should work exactly as in the video. It also sounds like a noise issue to me. It's possible that it's related to your previous issue - is it just doing this whilst running off your chargers? Could you try connecting it to a potentially cleaner supply like a PC USB port, or or better still a laptop port to see if this still happens. Also check the soldering on all the 100nF capacitors, especially C8, C10, C11, & C12 and the soldering on the pins of IC U2, U5, U6, U7 & U8 (especially the ground pins).

And finally.. when is the R.G.B morphing colour version coming out.... :D
We get asked about this every now and then. The problem is with an RGB cube everything gets multiplied up and it becomes difficult to come up with a simple design that's not overly expensive (the RGB LEDs alone will be a significant cost), or requires surface mount components such as a more powerful microcontroller or even an FPGA to drive the LEDs. If we can come up with an elegant solution we'll defiantly consider it.
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Ramshackle
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Joined: Tue Feb 19, 2019 7:36 pm

Re: Hobby Components 8x8x8 Cube Kit (HCKITS0050)

Post by Ramshackle » Thu Feb 28, 2019 9:05 pm

Many thanks for the reply, I’ll try and borrow a scope and see just how noisy the phone power supplies I am using are and maybe post some screen shots, it is very weird tho, I will touch up the caps and also try the power socket using my bench supply and report back, overall it was a complete success, worked first time apart from missing out plugging into one of the legs of the led lead onto the board, pilot error!

Just looking for a decent display case for it as I am sure the wife will want to dust it at some stage.... :o

Well done all round guys !

willy54584
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Re: Hobby Components 8x8x8 Cube Kit (HCKITS0050)

Post by willy54584 » Sat Mar 02, 2019 5:59 am

You would need enough addressable DACs to handle 343 LEDs. If you went with eight-channel DACs, that'd be 43 devices unless you used a clever analogue multiplexing scheme. You'd need a power supply (I purchased moon lamps for kids here and I think this is the best lamp for kids and I prefer to buy these lamps.) that could provide at least 6.86A (much less if you multiplexed). You'd need to build a jig to jig-solder all those LEDs together in such a way that it didn't just look like a mess.

Ramshackle
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Re: Hobby Components 8x8x8 Cube Kit (HCKITS0050)

Post by Ramshackle » Sat Mar 02, 2019 9:56 am

I was being a bit tongue in cheek with regards to the RGB version, it would be a complex build to design and execute, 512 leds with 4 legs I presume, all fully adressable is just mind blowing stuff, I have fully RGB tape and bulb style leds running on my arduino, the make superb Xmas lights that people always ask about :D

If your monitoring this Andrew, I went over the build of the panels of leds again when it was quiet in the house and found 2 whisker size ‘shorts’ on the leds, re soldering those sorted out the odd leds lighting where they shouldn’t, and the animations are now perfect... moral of the story is check, and check again then go away and check again :lol:

Seems to have made the power supply gremlins a lot better as well, though I will reflow all the caps and ic’s again and see if that helps.

andrew
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Re: Hobby Components 8x8x8 Cube Kit (HCKITS0050)

Post by andrew » Sat Mar 02, 2019 10:41 am

@Ramshackle
@willy54584

What would be nice is something like the WS2812B's in a 3mm LED package. That would make the design very simple.


@Ramshackle

That's great. it's still worth giving the caps another look over if you're still seeing noise issues though. At some point I could do with compiling a list of common problems and adding it to the front page but dry joints and unsoldered pins would be at the top.
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Ramshackle
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Joined: Tue Feb 19, 2019 7:36 pm

Re: Hobby Components 8x8x8 Cube Kit (HCKITS0050)

Post by Ramshackle » Sat Mar 02, 2019 3:09 pm

@Andrew, how awesome would that be, it does seem however the WS2812B's all seem to be smd’s, after a quick google, just 3 wires would make the design a lot easier I guess, I can’t believe they are not in the pipeline somewhere in the Far East.....

Re flow of the board in progress will post any changes.. :)

Ramshackle
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Joined: Tue Feb 19, 2019 7:36 pm

Re: Hobby Components 8x8x8 Cube Kit (HCKITS0050)

Post by Ramshackle » Tue Mar 05, 2019 7:30 pm

Hi Andrew, as promised a report back, and still have issues with erratic led behaviour.
Here’s what I have done so far..

Took all the 8 led frames from the board and checked all the leds again, 1,2,3,4,5 and 6 grids were fine, 7 and 8 when tested again, 3 leds on grid 7 and 4 leds on 8 were very dim and were drawing app 60ma forward biased and also reversed biased the same, replaced with the spares provided. All now working fine.

Went all over the board and retouched of the solder joints and looked for any misplaced components everything was fine.

Replaced each grid starting with grid 1 to 6(leds facing towards me) connecting up the positive to from the boards to each layer and powering up using my bench power supply set to 7.5 volts, unit boots up, displayed the boot sequence and the 5,4,3,2,1 double flash and started to run the pre programmed sequence.

Their was no erratic behaviour and worked wherever I plugged the cube in, whether using the bench supply, usb supply and using various types of usb phone supplies.

Time to install grid 7 and 8 - installed grid 7 and the display wouldn’t boot properly missing out the some of the text at the beginning and half of the countdown.

Added the last grid and it was back to not going to the boot stage and straight into the double flash of the feet, and then a very random sequence, blank for a few seconds then starting on something else - the sine wave would start, miss a row or just not complete, others would just not even start, moving my hand near the board would make it start working again but not as it should.

Taking out grid 7 and 8 again the cube would boot as normal....

I’m beginning to wonder if the almost dead short leds have damaged the I.c that powers the last 2 grid ? - should I swap one over and see if it causes problems on any of the other installed grids? (Edit... swapped and no change)

Sorry for the lengthy explanation but hoping it might help in diagnosing what’s wrong.

andrew
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Re: Hobby Components 8x8x8 Cube Kit (HCKITS0050)

Post by andrew » Wed Mar 06, 2019 10:15 am

Thanks again for the information....
connecting up the positive to from the boards to each layer and powering up using my bench power supply set to 7.5 volts
Time to install grid 7 and 8 - installed grid 7 and the display wouldn’t boot properly missing out the some of the text at the beginning and half of the countdown.

Assuming your bench PSU has a variable voltage output could you try upping the voltage a bit as 7.5V is right at the bottom limit and could be causing brownout issues. Ideally try it at 9V. Also whilst doing this could you check that the regulator (U4) is not getting hot to the touch - it should only get slightly warm at 9V input.


I’m beginning to wonder if the almost dead short leds have damaged the I.c that powers the last 2 grid ?
should I swap one over and see if it causes problems on any of the other installed grids?

For the problems with grid 7 and 8 this could be related to the above problem so if you could check that suggestion first before the following -

Grids 7 & 8 are controlled by IC U8. However the drivers on this IC are current limited so a short anywhere on the LED cube shouldn't be able to damage it. In fact you should be able to drop a set of keys on the cube and it wouldn't cause any damage to these ICs or the LEDs.

However that said, swapping the IC with either U4, U5 or U6 is a relatively easy test so worth trying. If there is anything wrong with them I'd expect the problem to shift to a different grid.

Also, I doubt that this is related to your problem, but could you check the batch code etched on to IC U3 (M54562p). Can you make sure it not '15210'.
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andrew
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Re: Hobby Components 8x8x8 Cube Kit (HCKITS0050)

Post by andrew » Wed Mar 06, 2019 10:21 am

Ah - just seen your edit. If you could try the first suggestion of upping the PSU voltage to the DC socket to 9V and if the problem still persists can you double check all the soldering around IC U8. One common issue we've seen is where when inserting the IC sockets into the PCB the odd pin on the socket can fold under the socket and not make contact with the PAD. This is very difficult to spot but if you happen to have a multimeter it's worth checking the continuity of the socket pins to the soldered pads on the PCB.
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