TITLE: Assembling LED Controller Electronics
AUTHORS: Jakub Nedbal

[DESCRIPTION]
<div class = "text-blocks"><div class = "text-block">The LED controller electronics regulates the LED current, adjusting the irradiance of the sample according the experimental needs. It also powers the fans cooling down the LEDs.</div><div class = "text-block"><span style = "font-weight:bold;">This document is part of the Illuminated Orbital Shaker for Microalgae Culture project:</span></div><div class = "text-block"><ul style = "list-style-type:disc;"><li style = "counter-reset:ol0;list-style-type:disc;">​Procuring Parts for Algal Shaker​</li><li style = "counter-reset:ol0;list-style-type:disc;"><span>​Assembling LED Controller Electronics </span><span style = "font-style:italic;">(this document)</span><span></span></li><li style = "counter-reset:ol0;list-style-type:disc;">​3D Printing Case for LED Controller​</li><li style = "counter-reset:ol0;list-style-type:disc;">​Assembling Cooled LED Illuminator​</li><li style = "counter-reset:ol0;list-style-type:disc;">​Cutting and Drilling Clear Acrylic Sheet​</li><li style = "counter-reset:ol0;list-style-type:disc;">​Assembling Algal Shaker</li></ul></div></div>

[STEPS]
?. Assembly of SMD ComponentsStart the assembly with all the SMD components first.Use a thin solder wire, solder flux, and watchmaker's tweezers to help with the soldering. The SMD components that need to be soldered are highlighted in the image below:
?. Adding the Power Supply ConnectionIn this step, the power supply connection is added and the first test of the circuit is performed.Solder the power supply connector (J1), toggle switch (SW1), the fuse holder (F1), and insert T1.25A fuse into the fuse holder according to the image below:​With the components soldered in place, connect the +30V power supply to DC power jack (J1). Make sure the T1.25A fuse is in the fuse holder (F1). Use a digital multimeter in the DC Voltage mode to probe the Voltages on test points of the board.Make sure the toggle switch (SW1) is in the position as shown in the image above. Connect the multimeter ground lead (black) to the test point labelled GND1 in the image above. Connect the positive lead (red) to the test point labelled +1.25V in the image above. The multimeter should show a value close to 1.25 V on the display. If it does not, check the soldering. On an occasion, we found the shunt reference D1 (MAX6006) failed after assembly and had to replace it. It may be that this component is quite sensitive to mishandling and so you may need to replace it if it does not work before proceeding to the next steps.Switch the toggle switch (SW1) to the opposite position to the one shown in the image above. With the multimeter ground lead connected to the GND2 test point, probe the Voltage at the testpoint labelled +30V. Make sure the measured Voltage is close to +30 V. If not, check the soldering. The only component that may be susceptible to failing due to mishandling is Q1. Check if it works and replace it if required.Do not proceed to the next steps, until you verified the circuit works as described above. Replacing components will become hard or impossible once the remaining large through-hole components are soldered to the PCB.
?. Adding the LED Current RegulationIn the next steps, the rotary switch and the input control jumper will be installed and tested.Solder in the 3-way header (JP1). Insert a jumper shunt across onto the two lower pins of the three way header (JP1) labelled INT. Solder a DIP-8 socket into the place for the rotary switch SW2, according to the image below (do not solder the rotary switch directly into the PCB):Now, insert the rotary switch into the DIP-8 socket that has just been soldered to the PCB, according to the figure below:With the switch in place and the +30V power supply connected to DC jack (J1), use a multimeter to test the Voltage between test points labelled GND and VAR. The Voltage measured should vary in steps of 1.25 V, 1.09 V, 0.93 V, 0.78 V, 0.62 V, 0.46 V, and 0.30 V, which are respective to rotary switch positions of •, 1, 2, 3, 4, 5, and 6. Check these Voltages for every rotary switch position. If any vary significantly, check the soldering and measure the resistances of the SMD resistors. Fix any loose soldering joints or erroneous component placement. If no Voltage can be measured at any position, make sure there is a jumper shunt in the correct position on the 3-way jumper (JP1), as described above.Do not proceed to the next steps, until you verified the circuit works as described above.
?. Adding the LED ControllerIn the final assembly step, the adjustable LED driver (DC1) is added together with the screw terminal connectors (J2−J7).Solder in all these components according to the image below:​This completes the circuit assembly. Do not test the function of the circuit with the LEDs just yet. The LED strip needs to be mounted onto the heatsink first, to avoid overheating of the LEDs at full power.
?. Cleaning the PCB from residual flux is important to avoid long-term corrosion and possible future reliability issues. There are professional PCB cleaners in spray, which dissolve the flux that can be wiped off together with the solvent.Instead, I use a widely available solvent isopropanol (isopropyl alcohol, IPA, propan-2-ol) for cleaning. Get a small tub just about fitting the PCB with a lid (an old margarine tub works fine).Place the PCB into the tub and cover it completely with the solvent (the parts do not need to be completely submerged).Close the lid and let it soak for at least 10 minutes (or even overnight). This should soften the flux.Use a toothbrush and a toothpick to rub and scrape off any flux deposits from the PCB.Empty the tub with the solvent according to local waste disposal regulations.Place the PCB back into the tub, cover it with fresh isopropanol, close the tub lid and let the board soak for additional 10 minutes.Brush and pick any residual flux.Flick any residual solvent from the board and let it dry.The above steps explained how to clean the flux from the printed circuit board for long-term reliability of the LED regulator circuit.
?. This document described the assembly process for the LED controller electronic circuit. The assembly took place in steps, each followed by test instructions to verify the function of the circuit before embarking on the next assembly steps. By the end, the circuit board is ready to be installed into a custom case, which is described in the 3D printing case for LED controller document.
?. ​LEDregulator Circuit: KiCAD files with the circuit diagram and PCB design files.​OrbitalShaker_ElectronicsPartsList.xlsx: Excel document listing all electronics and electrical parts, and fixing required in the assembly of the illuminated Orbital Shaker.​KiCAD: Cross platform and open source electronics design automation suite.
?. This document is part of the Illuminated Orbital Shaker for Microalgae Culture project:​Procuring Parts for Algal Shaker​​Assembling LED Controller Electronics (this document)3D Printing Case for LED Controller​Assembling Cooled LED Illuminator​​Cutting and Drilling Clear Acrylic Sheet​​Assembling Algal Shaker​