Why Light Curtains Fail — And How to Fix Them
A failed light curtain has the power to stop an entire production line. Not only that — it tends to kick off a troubleshooting spiral that can waste hours if you don’t know where to start looking for the problem first. Sometimes it’s a blocked beam. Other times it’s wiring. It’s trickier still when the fault is internal and won’t show itself without proper testing. Here’s a look at why these problems arise — and how to identify and troubleshoot them quickly.
5 Common reasons light curtains stop working
Light curtains are built for precision, but they rely on every component working in sync. Misalignment, electrical interference, or aging hardware can break that chain. And, unfortunately, not every failure is obvious. These are the issues that most often result in system shutdowns:
- Misalignment of emitter and receiver: Even a small bump to the frame or bracket can knock beams out of alignment. The system may still power up, but the protective field won’t be complete.
- Contamination on the lens: Dust, oil mist, or dried coolant can scatter or absorb the infrared beam. Some units detect it, some don’t.
- Cable fatigue or broken conductors: Movement over time — especially near hinged mounts — can stress cables until they break internally. That leads to intermittent faults or complete loss of power.
- Incorrect power supply voltage: Undervoltage won’t always cause total failure. But it can reduce beam strength or slow response time, both of which trigger nuisance trips.
- Internal board failure: Light curtains have internal electronics just like any sensor. A failed capacitor, corroded trace, or shorted IC can bring it down from the inside out.
Symptoms worth paying attention to
Like any system malfunction, light curtain failures kick off a root cause analysis to get to the bottom of a problem. During inspections and assessments, there are a few symptoms that can narrow the scope of concern and help you identify the true cause of the shutdown. If any of these show up — and especially if they show up recurrently — it’s time to take the unit offline for bench-level diagnostics:
- Unexpected trips when no object breaks the beam
- Inconsistent startup behavior or delayed reaction time
- Warning lights with no clear explanation
- Failed resets that persist across multiple power cycles
- No response from test input or remote signal checks
Pro tip: Service at the component level
At GES, we know how complex light curtain repairs can be. We take the time to approach them properly and we repair them just like we handle Servo Motors or AC & DC Motors — by isolating the problem, restoring full function, and confirming safety system integrity before it ever leaves our bench. Our diagnostics cover everything, including:
- Lens cleaning and beam alignment checks
- Full cable and connector integrity tests
- Voltage checks under load and cold start
- Board-level inspection for burned, damaged, or corroded components
- Live testing in a simulated guarded environment
Since we don’t rely on guesswork or visual checks alone, every light curtain repair goes through real-world verification, just like every other unit we service. We’ve seen light curtains fail just a few months after install — and we’ve brought 15-year-old units back to life. The difference isn’t always age. It’s maintenance, handling, and repair quality. When light curtains fail, you need more than a new part — you need a repair you can trust
Get affordable, reliable repairs
Dealing with a problematic light curtain? Now through the end of the month, GES is offering 10% OFF single repairs or 15% OFF 3+ repairs on safety equipment.
Extending light curtain lifespan through targeted repairs
Safety systems should always work as expected. A light curtain that’s constantly tripping — or worse, a system that’s failed entirely — isn’t an obstacle: It’s a call to action. Before looking for a quick fix or a workaround, ask yourself: What’s really causing this problem? A targeted repair isn’t just one that gets the system back up and running; it’s one that gives you peace of mind.
