LED Strip Tester





Introduction: LED Strip Tester

This one is quite simple - a tester for an LED strip for your TV repairs.

I had a bit of trouble with my LED TV. One of the LED strips went out, and my screen went black. Until I shone a flashlight straight into the screen and saw an image I had no idea what was wrong - the LEDs weren't working.

Let me apologise beforehand - I am not an electronics engineer, and I may make a few blunders along the way. I'm happy for any corrections or comments from more experienced makers!

Necessary materials:

3 9V batteries

A resistor

A bit of wiring


A breadboard

Gator clips


Step 1: Wire Up Your Batteries

My LED strips ran on 27V. For a 32" TV, strips generally have 9 LEDs each, and each LED is a 3V load, and they are connected in series.

If you connect 3 9V batteries in series, you will have a power supply that is just over 27V.

I used bluetac to get the wires to keep in contact with the terminals.

Step 2: Add a Resistor and Maybe an LED

LEDs don't handle high currents very well, so you need to put a resistor into your circuit.

I used a breadboard for this, but technically you could wire your resistor in series to the terminals of your battery pack. I used a 68k ohm resistor because it was the first one I found lying around. I also found a small blue LED (probably rated at 1.5V) that I put in the circuit. This was to test a strip that had failed short, and was conducting, but not lighting.

Step 3: Power the Strips

Find the terminals on each LED strip and wire the battery pack to them. Remember, LEDs are diodes and only take current in one direction, so if a strip doesn't work, make sure you wire it in reverse first.

If a strip doesn't light, it's probably broken.

Step 4: Test Your Strips



    • Epilog Challenge 9

      Epilog Challenge 9
    • Pocket-Sized Contest

      Pocket-Sized Contest
    • Science of Cooking

      Science of Cooking

    We have a be nice policy.
    Please be positive and constructive.




    You can do this but with a resistor and quite shortly. In industrial fixtures, Leds are usually driven with a constant current generator which adapts its output voltage to the load. In physics, voltage doesn't exist, it is only a simple way to show what intensity is passing through a known impedance. The resistor isn't optional, it protects the Leds against overcurrent.