A Step-by-Step Guide to Solving Problems Before the Show Starts

You’ve spent hours programming the perfect light show. The stage is set, the talent is ready, and the audience is waiting. Then, something goes wrong: a light is flickering, a moving head is spinning aimlessly, or an entire section of your rig is dark. In the world of live production, lighting issues can be frustrating and stressful. At NLFX Professional, our team has diagnosed and solved countless problems on event sites and in venues. This guide will walk you through how to troubleshoot some of the most common stage lighting issues, helping you get your show back on track.

Problem #1: A Single Light Fixture Isn't Working

This is the most common issue. Before you assume the fixture is broken, run through this checklist in order.

Is it plugged in?

It sounds simple, but always check the power connection first. Ensure the power cable is securely plugged into both the fixture and the power source. Try plugging a different, known-working device into the same outlet to confirm the outlet has power. Having a Circuit Que from NLfx in your gear bag will help with checking outlets ahead of time!

Is the DMX Address Correct?

Confirm that the DMX address set on the fixture matches the address you are trying to control on your lighting controller. A simple typo here is a very frequent cause of unresponsiveness.

Is the Fixture in the Right Mode?

Most modern fixtures can operate in different DMX channel modes (e.g., a simple 4-channel mode or an advanced 12-channel mode). Make sure the mode set on the fixture matches the fixture profile you've selected in your lighting software or console.

Check Your DMX Cables.

A single bad DMX cable can take down every light after it in the chain. Try swapping the DMX cable leading into the problematic fixture with a known-good cable. We always recommend using high-quality, reliable cables like our NLFX Pro Platinum Series DMX Cables to minimize these issues. Make sure you have an NLfx MOAT cable tester to go through any cables prior to your gig start time. 

Problem #2: Lights are Flickering or Behaving Erratically

Flickering or random strobing is often a sign of a DMX data problem.

Are You Using a DMX Terminator?

A DMX signal needs a "stop sign" at the end of the line. Without a DMX terminator plugged into the DMX output of the last fixture in your chain, the signal can reflect back down the line, causing data errors that manifest as flickering or erratic behavior. This is the most common cause and the easiest fix.

Are You Using Microphone Cables for DMX?

While a short run with a microphone cable might work in a pinch, they have the wrong impedance (70-80 ohms vs. 110-120 ohms for DMX). Over longer distances or with more fixtures, this impedance mismatch can corrupt the DMX signal. Always use true DMX cables for your lighting rig.

Problem #3: A Moving Head is Moving Randomly or Not Responding Correctly

When a moving head goes rogue, it's almost always a data issue.

Check Your DMX Patch and Addressing.

This is the most likely culprit. Double-check that the fixture's starting address is correct and that you haven't accidentally patched another light to the same address. Ensure the fixture profile in your controller (e.g., from Chauvet DJ or ADJ) matches the DMX mode set on the light itself.

Check Pan/Tilt Invert Settings.

If the light is moving opposite to your commands, check the Pan or Tilt Invert settings on either the fixture's menu or within your lighting software. It's an easy setting to miss.

Problem #4: The Entire DMX Chain is Unresponsive

If none of your lights are responding to the controller, start at the beginning of the signal chain.

1. Is the Controller Working?

   Check that your lighting controller has power and is sending a DMX signal. Most controllers have an indicator light that shows DMX output.

2. Check the First Cable.

   The DMX cable running from your controller to the first light is the most critical. If that cable is bad, the entire system will fail. Swap it out with a known-good cable to test.

While lighting issues can be stressful, a systematic approach to troubleshooting can solve most common problems quickly. The best defense, however, is a good offense: starting with high-quality, reliable cables and gear will always save you headaches in the long run.

Still stuck? If you have a fixture that needs professional attention, contact the expert technicians in the NLFX Pro Repair Center today!