Troubleshooting LED Strip Problems

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LED strips come in a very wide variety of sizes, densities and color quality, but what they all have in common is that at some point, you may run into some difficulty getting them to work. Through our many years of working with LED strips, we've put together some of the most common causes of LED strip problems and what you can do to solve them.

CAUTION: Low voltage DC electronics are generally considered safe and pose a relatively low shock hazard. However, whenever possible, we strongly recommend that you turn off the power to, or unplug, the power supply prior to testing or adjusting any LED strips or accessories.

Note that in some troubleshooting steps we suggest below, you will need to have the power supply plugged in and powered up to complete the test. Use caution and seek the advice of a qualified individual if you are not sure how to perform these tests safely.

LED strip does not light up at all

You've connected the power supply to the LED strip, turned the switch on, and...nothing. What gives?

To troubleshoot, try the following steps:

1) Confirm that your power supply's voltage and current rating are compatible with your LED strip.

If, for example, your power supply is 12V DC, it will not work with a 24V LED strip. Check the back of the power supply unit, which will have the output voltage marked. Then, check the LED strip itself, which will have its input voltage marked at the LED strip connection points.

2) Confirm that your power supply is working correctly.

A quick test using a multimeter to verify the voltage across the two output wires, or voltage between the DC plug's inner pin and outer barrel should indicate a voltage differential. If it shows a voltage less than its rated voltage, you may have a malfunctioning power supply.

Note that the power supply must be powered up for this test.

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3) Check and isolate other accessories on the same circuit.

Remove any optional dimmers and controllers from the circuit, and determine if you can get the LED strip to illuminate without the extra accessories. If the LED strip works, that means you have a problem with the dimmer or controller, or the connection leading up to or from those accessories.

Note that the power supply must be powered up for this test.

This should go without saying, but never connect a low voltage DC (e.g. 12V/24V) LED strip directly to a mains voltage (e.g. 120V/240V) wall outlet!

4) Check for any visible loose connections

Make sure all of your connectors and wires are in place and have not fallen out. Try tightening screws on DC adapters, and re-inserting LED strips into solderless connectors, which are common contact failure points.

If you have a multimeter, test each point along the circuit for a voltage differential between the positive and negative (ground) wires / terminals. Start at the power supply's DC output and make your way to the LED strip. If the LED strip's positive and negative copper pads do not have a voltage differential, power is not being fed to the LED strip due to a malfunction before the power can even reach the LED strip section.

5) Check for any visible signs of short circuits

Especially if you are soldering your own wires instead of using solderless accessories, you may have inadvertently created a short circuit by allowing the positive and negative wires to come in contact.

Perform a quick visual check of your entire LED strip connections and ensure that these wires are sufficiently separated.

Short circuits of this type are especially more likely when working with multi-channel strip lights such as 5-color LED strips which have 6 connection points.

6) Check for invisible signs of short circuits

If after a visual check you did not find any visible short circuits, you may next want to check for invisible short circuits. The quickest way to test this is to again, use a multimeter.

Apply the multimeter contacts to the positive (+) and negative (-) copper pads on the LED strip, and test for the resistance value. If there is no short circuit, the multimeter should indicate infinite resistance. If it indicates any resistance value, that indicates that there is a short circuit.

If there is an indication of a short circuit, disconnect any accessories and wires, and determine if the short circuit on the LED strip persists. If it does, this is an indication that there is an issue with the LED strip.

One common short circuit location is the cut-line of the LED strip where scissors were used. LED strips are typically constructed of two copper layers, separated by a thin layer of insulation. In some cases, if the scissors do not make a clean cut, the insulating layer may fail at the cut point, creating a short circuit.

If you've identified a short circuit on an LED strip segment but cannot find any visible signs of a short circuit location, try cutting off the last 1-2 inches of the LED strip on both ends to remove the potentially damaged cut-line segment. We recommend using a sharp pair of scissors to ensure a clean cut, as dulled, blunt scissors are more likely to "squash" the copper and insulation layers, creating the short circuit.

LED Strip is Dim at One End

Is your LED strip running fine, but exhibiting a noticeably lower brightness at one end? This is a commonly observed issue with lower quality LED strips, and its primary cause is voltage drop.

Voltage drop is essentially caused by excessive electrical current for a given circuit design, or excessive resistance in the circuitry, or a combination of both.

Check your Circuit Design

Most LED strips will have a recommended max run length based on its power draw per foot and the internal circuit design. Because each section of LED strip must carry the current for all "downstream" LED strip segments, connecting too long of an LED strip will exceed the power rating for the LED strip sections connected closest to the power source.

The most immediate consequence of overloading an LED strip with too much power is voltage drop, whereby the voltage supplied to each section of LED strip progressively decreases as one moves further away from the power supply. The reason the voltage decreases is due to the internal resistance in the copper traces of the PCB.

Don't forget that wires connecting to or between LED strips also have internal resistance, and using wires with insufficient thickness can also result in excessive voltage drop. Check out our online wire gauge calculator to see if your wire spec is sufficient for your setup.

Perhaps you may be able to rearrange your circuit be configured in "parallel" as opposed to "series."

Check for Electrical Resistance

Excessive electrical resistance can be caused by poor electrical contact and corroded copper. Check your LED strip wiring and ensure all contacts are clean and sufficient.

In extreme cases, poor contact points can heat up, leading to a fire hazard, so determining and eliminating these situations can be an important safety check.

Diagnosing Voltage Drop

The most definitive way to determine if voltage drop is causing issues for your LED strip is to simply measure the voltage between the copper pads at various points along the LED strip. If the voltage progressively decreases as you move further away from the power source, this is a sign of voltage drop.

Almost all LED strips will exhibit some voltage drop, and whether it becomes a significant problem or not primarily depends on the extent of the voltage drop. For example, a 12V LED strip may drop to 11.5V at the end furthest from the power supply, but this is typically not a significant enough voltage drop to warrant any concern. If, on the other hand, voltage drops to below 10V, this is a sign that there is a significant amount of voltage drop that is very likely producing a very noticeable brightness drop.

LED strip is getting dim over time

If your LED strips are losing brightness across the entire strip, this could be caused by two issues:

1) Input voltage into the LED strip has dropped below the designed voltage

To determine which of these two issues is to blame, first determine the input voltage at the point where the LED strip is connected to the power supply (i.e. the first pair of copper pads).

If the input voltage here is below the expected voltage (e.g. 10V for a 12V LED strip) you are likely seeing an issue with the power supply or a loose / corroded connection between the LED strip and the power supply.

The good news is that your LED strip is likely in OK shape, and simply correcting your wiring or replacing your power supply will resolve your issue.

2) The LEDs themselves are losing brightness

If in the first test you determined that the LED strips are being fed the full design input voltage (e.g. 12V for a 12V system) but you are still seeing a brightness drop, you may have a serious issue with the LED strip.

LEDs are generally designed to last more than 36k hours, but some lower quality products will cut corners in design and manufacturing, leading to premature failures. In such situations, your only choice may be to replace the LED strip entirely.

LED strip adhesive is losing adhesion

If parts of your LED strip are falling from their mounted surface, you may have used an LED strip with insufficient double sided tape. You can consider reapplying a new layer of double sided tape, or using some mounting brackets and screws for a more permanent mounting method.

We recommend "sticking" with higher quality LED strip lights, which are more likely to specify higher adhesion double sided tape, such as 3M VHB.

LED strip has sections that do not light up

If you have an entire LED strip segment illuminated but notice a section of 3 LEDs (or 6 LEDs for 24V) that remain dark, you may have an "open circuit" in one of the sections.

What this means is that due to a manufacturing flaw or some mechanical damage during shipping or installation, one of the LEDs or components for a single section has come loose, resulting in a complete electrical disjoint for just that section of LEDs.

If you are familiar with how to solder, you may want to try reheating the solder joints for each of the LEDs and components along that dead section. If not, your best bet would be to ask your supplier for a replacement (if they provide a warranty) or simply remove the failed section by cutting along the cut-lines and rejoining the two segments together using connector clips.


Still haven't resolved your issue?

Waveform Lighting manufactures LED strips to exacting quality and reliability specifications in order to avoid common issues like the ones outlined above. Unfortunately the same cannot be said for many other "budget" LED strip lights that are available for purchase.

Please contact us immediately if you have an issue with an LED strip light that you purchased from us. Even if you're having trouble with an LED strip light that you purchased elsewhere, we'd be more than happy to help and discuss replacement options.

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