Fixing and Improving My Ring Light

I bought a ring light to take photos of my Instructables projects, but later on, I decided to purchase a professional video light. I have been using this light as a working light, but one day, while it was on, I noticed smoke coming from its control circuit. The light is malfunctioning, so I will fix it and add a wireless control function. This way, I won't have to reach for the controller whenever I want to adjust the brightness. I will guide you through fixing the light and adding the wireless control function. Let's get started!

Parts used for modification 

• Seeed Studio XIAO ESP32C3
• 2*IRLZ44N  ( any mosfet that works on the logic level )
• 2*10 resisters 
• Double Sided Protoboard Breadboard 3x7 cm
• Replacement LED ( optional )

Tools 

• Dual Ends Metal Pry Bar Crowbar Kit
• Soldering iron kit
• Kapton tape
• PTC Heating Plate
• Adjustable DC Power Supply
• Tweezers 
• Screwdriver set

First of all, we need to know what happened here, also it is good to understand why it is damaged. We can take precautions to prevent it from happening again. 

Let’s start the process by opening it 

Step 1:1

First, open its control circuit. it doesn’t use any screws so we can open it with a flat screwdriver or par bar tool

Step 1:2

Let's examine the circuit board more closely. It seems like there was some kind of fireworks display happening here 😂. The circuit contains only one main chip, which has burnt out, along with the resistors. I tried searching online for some PCB photos and teardowns, but I couldn't find anything about replacement parts. Regardless, we are going to rebuild the entire LED control circuit. 

Step 1:3

I think we should analyze why the issue occurred. In my opinion, the main reason is the poor quality USB power supply that I used. It came with the extension board I used, and it can cause high voltage peaks that may damage the connected electronics. Therefore, the best precautionary measure is to avoid using untrusted power supplies.

We need to ensure our LEDs are functioning properly, in addition to fixing the issue with our control circuit.

Step 2:1

To open the front diffuser of the ring light, use a pry bar tool.

Step 2:2

Now, we need to power up the LEDs and check if all of them work. We have 3 wires going into the LED. 

1. Common ground 
2. Warm LED 
3. Cool LED

Desolder the wires from the PCB 

All LEDs are connected in parallel so we need to power it up with a 3.3V source and check that all LEDs are lit. ima using an adjustable power supply for it. a battery will also work.

For me all LEDs are fine. what if you have any problem with your LEDs, how to replace them? I will show you in the next step 

Step 3.1

Remove the screws that hold the LED panel in place, and then carefully take out the LED PCB.

If you need replacement LEDs,2835 SMD LEDs are used here and have two temperature types. also pay attention to the polarity of the LED. the biggest pad is always the ground of the LED

link to buy this 

https://www.ebay.com/itm/334388611835

Step 3.2

There are two ways to replace the LEDs 

• With PTC Heating Plate
• With soldering iron 

It is not recommended for inexperienced users to use a hot air rework station as it can damage the LEDs. The other two methods mentioned are easier to perform compared to hot air.

Method 1: PTC Heating Plate

Connect your heating plate to the mains voltage, wait for it to heat up and place the PCB on top of it. Use something to hold the PCB in place. and use a tweezer to remove defective LEDs

Now take one working LED and plate it on top of the soldering pad 

Method 2: Soldering Iron 

If you don't have a heating plate, a soldering iron should be enough. We can heat the PCB by placing it on top of the soldering iron. Place something in the tip of the soldering iron for support.

Step 3.3

After this replacement power the LEDs and check if all the LEDs are working fine 

Step 3.4

Now screw the led pcb back into the enclosure and put the diffuser on 

To rebuild the control circuit that is based on an open-source project called WLED. we are using a Xiao esp32 for running WLED. we also need 2 MOSFET to control the LEDs

Step 4:1

 First of all, we need to flash WLED into our xiao i already covered this topic in one of my previous Instructables https://www.instructables.com/WLED-ON-XIAO-ESP32/. Follow these Instructables  to install the WLED

Step 4:2 

We need to cover some exposed copper pads on the back of Xiao with  some Kempton tap 

Step 4:3 

We can start our circuit assembly by soldering Xiao onto the prototype board 

Step 4:4

Bend the leads of the Mosfet about 90° and Solder two mosfet into the PCB

Step 4:5

Solder a 10k resistor between the gain and drain of both mosfet

Step 4:6

 Then complete the rest of the wiring according to the wiring diagram 

Step 4:7

We can use the desoldered USB power wire from the ring light to power our circuit 

Step 4:8

Now connect the LED wires to the MOSFET drains. Also to the +5v

We just completed our control circuit assembly 

We cannot use the old enclosure for the new controller circuit because it is too big. So we need to design an enclosure that will fit our new circuit board with our Fusion 360 

Here is a quick rundown of my design process

1. Started by measuring the dimensions of the PCB
2. Made an 80mm x 30mmx12mm box 
3. Made a round edge within all 4 corners with Fillet tool 
4. Covert it to a 1 mm shell using a shell tool 
5. Made a small gap for the wires 
6. Made a cap with the Project tool

After creating the 3D models, I exported them as .stl files and sliced them using 3D model slicing software to generate Gcode for my 3D printer. 

After completing the 3D printing of the enclosure, the next step is to proceed with the final assembly of our project.

Step 7:1

Push the PCB inside the main body. My PCB is holding up without the help of glue and screws because of the good tolerances in my 3d printing. you secure it with some hot glue if you need it. Also, put the wires through the small side gaps

Step 7:2

Install the antenna that comes with the xiao into the back side of the top cap 

Step 7:3

Plug in the antenna cable to Xiao

Step 7:4 

Also, the top cap will snap in place with the help of any screws 

We just completed the full assembly 

Now power up our project using a USB power supply and using my 5v mobile charger for it . as I mentioned in my instructables. Xiao will automatically connect to your WiFi network. To control the LEDs, you'll need to have a mobile device with the WLED app installed and connected to the same WiFi network.

WLED app install links

• IOS
• Android 

Open the app

+ Sign > Discover light > Found WLED so click the ✅> Select your device .Config > LED Preferences > Select the LED output. Change it to PMW CCT > Please enter the GPIO pins 9 and 8 which are connected to the MOSFET controlling the LEDs.

Don't forget to click save before closing the configuration, otherwise the changes we made won't take effect.

LED temperature and brightness are now adjustable with sliders. Try it!

well, it is working wonderfully. you can use these same technics to modify and fix LED lamps. WLED projects still deliver more functions to your light. like you can set a certain value of brightness for every time is powered on. you can control more light on the same app, set up auto wakeup time etc..

https://github.com/Aircoookie/WLED

here is the project git you can explore more about it here