LED Cube/PCB Soldering Manual

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LED Cube Series


Chapter 1: Build

Section 0: Preparation and Requirements

Section 1: PCB Soldering Manual

Section 2: Cube Soldering Manual

Section 3: Assembly and Testing

Chapter 2: Play

Using the Cube

Creating an Animation

Chapter 3: Learn

Understanding the Electronics

Custom Programs

This page contains the soldering manual for the PCB of the LED Cube.

A full schematic of the PCB can be downloaded here: Datei:Cube.pdf.

USB Resistors


First we solder R10, R11 and R13. As all resistors we are using in this project, their orientation is not relevant. You can see the resistor values in the schematic or in the table below, together with the color code marking:

Name Value Color Code
R10 68 Ohm R-68.jpeg
R11 68 Ohm R-68.jpeg
R13 1500 Ohm R-1500.jpeg

First bend both leads about 90 degrees, so they fit into the two holes. The distance between the leads, as with every resistor we will solder on this board, is about 11 mm, but it is not important to be very accurate here. Place them into the holes and flip the PCB.

To solder them, get your already heated soldering iron, clean it with a moist sponge or the tools that available. Apply a very small amount of solder to the tip - just enough so that there is a small film of solder on it. We will need this solder only for the iron to be able to heat up the PCB and the resistors - we will add more solder later.

and solder them on the back side. Afterwards, clip away any excess wire, but do not damage the solder joint by clipping away more than necessary.

USB Zener Diodes


Additionally, we need two 3.6 V Zener diodes for the data lines, Z1 and Z2. Here, you have to pay attention to their orientation. The (black) line on the diode is the same as the single line on the symbol (as opposed to the triangle) that is printed onto the PCB. You can see that in the figure on the left.

The solder process looks just like the one of the resistors, but this time, if you want to be accurate, you have to bend the diode legs so they are 7.5 mm apart.

Reset Resistor


The Reset pin gets a 10 kOhm resistor R12 to the 5 V line. Again, have a look in the table for the correct color markings. Orientation is irrelevant.

Name Value Color Code
R12 10 kOhm R-10000.jpeg

Column Resistors


If you bought a kit or attend a workshop, you probably already got the correct Resistors. There should be (at least) nine of the same value. Just solder them into the places for R1 to R9.

If you are supplying your own LEDs or did not get matching resistors for any other reason, you have to pay attention: The ideal column resistors should be chosen for each LED color separately. You are always on the safe side, if you choose a high value, but then your cube may not be as bright as you want it to be. If you are interested in this, read LED Cube/Column Resistors in Detail. Alternatively, here is a table of common colors, their forward voltages and the recommended resistor value:

Color Forward
Resistor Value
(nearest @15 mA)
Color Code
Red 1.9 V 120 Ohm R-120.jpeg
Blue 3.0 V 56 Ohm R-56.jpeg
White 3.0 V 56 Ohm R-56.jpeg

Column and Plane Connectors


Now add the column and plane connectors to CONN1 to CONN10. This step is optional and it is probably the most annoying part of this PCB, but you should think twice before you skip it: It allows you to disconnect and reconnect your cube without expensive equipment. And do repairs on it which may not be possible while it is connected. But it's your choice - skipping this step does not have any other significant effect.

So, to add the connectors, we first have to separate them from the break-away header row. You can do this with a scalpel or side cutters. You will need nine single-pin connectors and one 3-pin connector. You can also completely remove the plastic around them if you want. Now put one by one into the pcb, and solder them. You do not have to cut away any excess wire afterwards. You may however try to reheat some solder joints and wiggle on them, if the connectors are not straight.


We need four capacitors, two times 100 nF (C1, C2) and two times 22 pF (C3, C4). See the schematic at the left or the table below for their values and positions. Again, all four devices are symmetric and orientation is irrelevant.

Name Value Marking
C1 100 nF Lcpcb-05-01.jpg (104 ≙ 10 * 10^4 pF = 100 nF)
C2 100 nF Lcpcb-05-01.jpg (104 ≙ 10 * 10^4 pF = 100 nF)
C3 22 pF Lcpcb-05-00.jpg (220 or 22 ≙ 22 * 10^0 pF = 22 pF)
C4 22 pF Lcpcb-05-00.jpg (220 or 22 ≙ 22 * 10^0 pF = 22 pF)


Now you should add the 16 MHz crystal U3. You do not have to care about its orientation.

Transistor Array


Now add the transistor array U2.

But first we have to make sure it fits. If you have a look at the following picture you can clearly see that the way the IC got deliviered to you, has pins that are tilted:

To get them straight, take the IC with both hands and put it on a flat surface. Then slowly bend it forward until the legs are straight.

Now you see that it fits.

Before soldering, make sure that the notches are correctly aligned. You will find one on the IC itself and one on the PCB.

Microcontroller socket


Add the microcontroller socket to the PCB at U1. As with the Transistor array, there is a small marker on the package which should be on the same side as the marker on the PCB.

USB Socket


Now add the USB socket. This should be straightforward. You should solder the two big shield connectors on the side, not just plug them in, to increase the stability.

Bootloader Jumper

Now we need the bootloader Jumper CONN12.

Imbox move.png

This was the first part of this tutorial. You should continue with Section 2: Cube Soldering Manual.