Hobby Components 8x8x8 Cube Kit (HCKITS0050)

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

Post by andrew » Tue Oct 17, 2017 8:51 am

Yes, swapped ICs around, same rows failed
Thanks for checking. I really expected the problem columns to have moved. IC's U5 to U8 control each column of LEDs. U5 controls columns 11 to 28 and U7 controls columns 51 to 68 which happen to be the columns that aren't working. So this points to a problems with those two IC's. However if that was the case then swapping them with the working IC's should have moved the problem to the other columns. Also the data pins on these ICs are daisy-chained (cascaded) so if U7 was dead U8 wouldn't work and if U5 was dead none of them would work. I would next point at the actual columns of LEDs but you have already checked them.

My next thought is the components around U5 and U7. The only components I can see that could cause this problem are resistors R8 and R10. Looking at the original image you posted I can see that you have fitted the correct values (1K) but can you check the soldering for these two components. I can see some flux around R8, was there issue with it?

Failing this I'm not sure what else it could be. If you still have no luck I'll take a look at the PCB layout to see if its possible for a problem with a track or a short somewhere to cause this issue.
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motorwrists
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Re: Hobby Components 8x8x8 Cube Kit (HCKITS0050)

Post by motorwrists » Tue Oct 17, 2017 1:04 pm

Hi Thanks again much appreciated. I did have problems with R8 (I though I put the wrong component in, removed and then realised it was the correct one and put it back - doh). is there any way to test if this is the cause, repair or work around it? R10 is OK I think.

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

Post by andrew » Tue Oct 17, 2017 3:34 pm

A problem with R8 would explain why columns 11 to 28 wouldn't work but it wouldn't explain columns 51 to 68. That said, I still think it's defiantly worth looking at just in case there are two separate problems. It's possible when it was unsoldered it may have damaged one of the through-hole platings which connect the pads on each side of the PCB together. If so then the easiest way to repair it is to solder the resistor legs on both sides of the PCB. If you could give that a try and see if it at least fixes columns 11 to 28.

I've looked at the track layout but I can't see any place where a single issue could exist that would only effect those those particular columns and not the others. So I don't think that's where the issue is.
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motorwrists
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Re: Hobby Components 8x8x8 Cube Kit (HCKITS0050)

Post by motorwrists » Tue Oct 17, 2017 4:24 pm

Hi, Tried soldering both sides. Only change now seems to be column 47 has stopped working (may have missed this before), 57 is still lighting up. Sometimes takes a minute or so from power on till LEDs animate. I have attached another image of underside. I have a multimeter if that can help troubleshoot. Thanks for all your help.
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andrew
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Re: Hobby Components 8x8x8 Cube Kit (HCKITS0050)

Post by andrew » Wed Oct 18, 2017 8:50 am

Thanks again for your answers. This is getting more puzzling. So to summarise the issues (mainly to clarify it in my own head)...


Columns 11 to 28 & 51 to 68 don't light up - These are the columns controlled by IC's U5 and U7 but swapping these IC's for working ones doesn't make these columns light up. This suggests there's nothing wrong with the IC's themselves. The only other components that would have a direct effect on these columns is resistors R8 and R10 but these seem to be ok.

Column 57 is lighting but dimly and column 47 is not working which may or may not be a new issue. I think it is best to ignore these for now as although they could be related to the above problem they probably aren't and may just muddy the issue.

Sometimes it is taking over a minute for the LEDs to light up. This defiantly shouldn't be happening and points to a more fundamental problem. Can you check/confirm the following things:

1) That when the LEDs illuminate they do appear to be playing the animations. I.e. they flash on and off randomly and are not just staying permanently on or off.

2) That when power is first connected the four 10mm base LEDs illuminate and then after about 10 to 15 seconds they flash on and off a few times.

3) With your multimeter can you measure the power supply voltage across pins VCC and GND of the serial header. Let me know what voltage you measure but if you can the keep the meter connected for a minute can you also check that the power supply voltage doesn't drift or suddenly dip.

Edit:

4) Can you check that none of the components, especially the IC's are getting hot to the touch.
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motorwrists
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Re: Hobby Components 8x8x8 Cube Kit (HCKITS0050)

Post by motorwrists » Wed Oct 18, 2017 11:31 am

Columns 11 to 28 & 51 to 68 don't light up - These are the columns controlled by IC's U5 and U7 but swapping these IC's for working ones doesn't make these columns light up. This suggests there's nothing wrong with the IC's themselves. The only other components that would have a direct effect on these columns is resistors R8 and R10 but these seem to be ok. - This is correct, 31-38/41-48/71-78/81-88 are working

Sometimes it is taking over a minute for the LEDs to light up. This defiantly shouldn't be happening and points to a more fundamental problem. Can you check/confirm the following things:

1) That when the LEDs illuminate they do appear to be playing the animations. I.e. they flash on and off randomly and are not just staying permanently on or off.
Animations play as expected, same as YT video. When i press reset button there is a approx. 10 second pause before it starts to loop through animation


2) That when power is first connected the four 10mm base LEDs illuminate and then after about 10 to 15 seconds they flash on and off a few times.Yes this happens

3) With your multimeter can you measure the power supply voltage across pins VCC and GND of the serial header. Let me know what voltage you measure but if you can the keep the meter connected for a minute can you also check that the power supply voltage doesn't drift or suddenly dip.VCC 1.5 mV GRD 2.6 mV

Edit:

4) Can you check that none of the components, especially the IC's are getting hot to the touch. All IC's remain cool (10 minutes of power)

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

Post by andrew » Wed Oct 18, 2017 2:42 pm

VCC 1.5 mV GRD 2.6 mV
Sorry I should have been more clear with this question:

Can you put your meter on its DC volts range and place the negative lead on the GND pin, and the positive lead on the VCC pin of the serial connector whilst the USB cable is connected. It's a little bit fiddly as the two pins are next to each other. You should read a voltage of around 5V. Can you let me know what voltage you actually measure and does it drift or dip over the space of about a minute?
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motorwrists
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Re: Hobby Components 8x8x8 Cube Kit (HCKITS0050)

Post by motorwrists » Wed Oct 18, 2017 2:53 pm

Thanks for explaination. Reading between 4.55 and 4.8 v. Pretty steady over a minute or so

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

Post by andrew » Thu Oct 19, 2017 8:34 am

Thanks again, 4.55V is a little low but I wouldn't expect it to cause a problem. Your answers to my questions have been very accurate but unfortunately they don't seem to be providing any clues as to where the problem(s) is/are. For the columns it really can only be ICs U5 and U7, the tracks/soldering to them, or the actual LEDs themselves. However from the evidence they all seem to be working fine. I'm going to have another think to see if I can come up with any other potential source of the problem but I think we may have to look at getting the base board back to us to debug it here.

In the meantime do you have any other USB power source you can try such as a different computer? Just in case it's a power supply issue.
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motorwrists
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Re: Hobby Components 8x8x8 Cube Kit (HCKITS0050)

Post by motorwrists » Thu Oct 19, 2017 9:55 am

Would iphone power supply be suitable?

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