Problems & solutions
Sign does not light up
The sign stays dark, does not switch on as scheduled, or only one letter or section is out.
Short answer
A sign that does not light usually points to the power path: breaker, 220/230 V feed, power supply, control device or connection. If only one letter or section is dark, the fault is more likely local: cable, terminal, polarity or LED modules. Burning smell, sparks, heat, water or a breaker that trips again are reasons to isolate the sign if safe and call a specialist.
Sign does not light up: causes, diagnosis and what to do next
Symptoms
The sign has stopped lighting. It does not come on through the timer, does not respond to the switch, stays dark in the evening, or went out during operation.
The whole installation may be dark: letters, lightbox, logo or contour lighting. In other cases the issue is local: one letter, one panel, one edge of a lightbox, or one LED module group.
The fault can happen suddenly after a storm or voltage spike. It can also appear after rain, snow, facade washing, renovation work or with no obvious trigger. Older signs often lead the diagnosis toward the power supply, terminals and wiring. Newer signs are more often checked for connection, breaker, load and wiring layout.
What This Usually Means
When the entire sign is dark, the first area to check is the power chain. The fault may be at the breaker, 220/230 V feed, power supply, timer, photocell, relay, controller or a main connection.
The power supply is a common cause, but it should not be assumed. A tripped breaker, loose cable, oxidized terminal, moisture inside the cabinet or a secondary-side short can look exactly the same to the customer.
If only one section is dark, the fault is more likely local: cable between letters, terminal, polarity, LED module group or a separate power supply feeding that zone.
Diagnosis by Visible Pattern
| What the customer sees | What it may indicate | What a technician checks |
|---|---|---|
| Whole sign is dark | No incoming power, tripped breaker, failed power supply or control device | Breaker, 220/230 V feed, power supply input and output |
| Went dark after a storm or surge | Protection may have tripped, or the power supply may be damaged | Protection, power supply, input line, heat marks |
| Fails after rain | Moisture, corrosion or leakage current is possible | Enclosure, cable entries, terminals, seals |
| Breaker trips on switch-on | Possible short circuit, moisture or damaged cable | Feed line, power supply, secondary wiring, enclosure |
| Timer works but sign stays dark | Power may not pass after the timer or relay | Timer, relay, voltage before and after switching |
| One letter is dark | Local open circuit, bad contact or LED module failure | Inter-letter cable, terminals, LED modules, polarity |
| Flickered first, then failed | Power supply or contact may have been unstable | Power supply, load, heat, connections |
| Burning smell, sparks, crackling or heat | Electrical risk | Isolate if safe and do not operate before inspection |
Main Causes
1. No Incoming Power or a Tripped Breaker
A sign cannot light if it is not receiving power. A breaker or RCD may trip because of overload, moisture, a short circuit, lightning or work on the same electrical line.
If the breaker trips again after reset, repeated testing is not useful. It can make the damage worse, especially when water or a damaged cable is involved.
2. Failed Power Supply
The power supply feeds the LED modules at the correct voltage. It runs under load, generates heat and ages over time.
Before a complete failure, a sign may flicker, start late or behave inconsistently. A sudden blackout without warning is also possible.
Replacing the power supply without checking the system is risky. Voltage, power reserve, protection rating, cooling and the reason the old unit failed all matter.
3. Loose or Damaged Cable
A cable can loosen at a terminal, inside a junction box, near the power supply, after a timer or at the cable entry. Vibration, old connections, poor installation or nearby building work can all cause this.
Damage is not always visible from the outside. It may sit inside the cabinet, in a wall, at the gland or in a connection box.
4. Moisture and Corrosion
Outdoor signs face rain, snow, condensation, temperature changes and wind. Water can enter through a cable gland, old sealant, lid, screw hole or mounting point.
Moisture causes corrosion, leakage paths, high-resistance contacts and short circuits. The sign may fail after the rain rather than during it, once condensation and oxidation have had time to affect the contacts.
5. Faulty Timer, Photocell, Relay or Controller
Automatically switched signs depend on more than the LED modules. A timer, photocell, relay, dimmer or controller can block power even when the sign itself is otherwise serviceable.
A typical clue is a sign that fails at the programmed switch-on time, or works manually but not automatically.
6. Short Circuit or Fault After the Power Supply
Even when the power supply receives input power, the LED side can stop the system. Damaged secondary wiring, reversed polarity, moisture or a failed module can push the power supply into protection mode.
In that case the power supply may look dead, while the real fault is downstream.
7. Local LED Module Failure
If one letter, one edge or one section is dark, the check becomes local: cable, terminal, polarity, LED module string and enclosure condition.
Replacing LED modules without checking power and moisture is a weak repair. If the underlying issue is water, poor contact or overload, the new modules can fail again.
What You Can Safely Check Yourself
Keep checks external:
- normal switch;
- breaker or RCD;
- external timer;
- other equipment on the same circuit;
- when the fault appeared;
- photos of the full sign and the dark area.
If the power supply label is safely visible without opening anything, photograph it. Do not touch wires or terminals.
What Not To Do
Do not open the sign cabinet, touch 220/230 V wiring, move terminals, install a similar-looking power supply, make temporary wire connections or fit a higher-rated breaker.
Do not keep switching the sign back on if there is smell, sparks, crackling, heat, water or a breaker that trips again.
When It Is Urgent
Treat the case as urgent if there is a burning smell, sparks, crackling, strong heat, water inside the cabinet, a damaged cable, exposed conductors, a tripping breaker or any need to access the sign at height.
If power can be isolated safely, leave the sign off until it is checked.
How PixelRing Diagnoses It
First, PixelRing clarifies whether the whole sign or only one part is out, and what happened shortly before the failure. Photos and a short description usually point the first inspection in the right direction.
On site, PixelRing checks the feed, breaker, power supply, output voltage, controls, cables, terminals, polarity, moisture, heat marks and LED modules. The aim is to find where the circuit stops working, not to replace the first suspicious part.
How The Problem Is Usually Solved
Depending on the cause, the fix may be a restored connection, repaired control device or correctly specified power supply replacement. If moisture is involved, the entry path must also be found and sealed.
For local faults, the repair may be limited to one letter, section, cable or module group. For input-side faults, the whole sign can remain dark.
What Affects The Scope
Access height, location of the power supply, size of the sign, number of letters or sections, cable condition, moisture traces, control devices and partial disassembly all affect the work scope.
What To Send PixelRing For a First Assessment
- current photo of the sign;
- previous illuminated photo, if available;
- close-up of the dark area;
- address and mounting height;
- approximate age of the sign;
- when and how the fault appeared;
- whether the breaker trips;
- smell, noise, heat, water or visible cable damage.
Related Situations
- Sign flickers
- One letter does not light
- Sign fails after rain
- Uneven LED brightness
- Lighting comes on and immediately goes out
- Urgent sign repair
Common causes
- No incoming power, tripped breaker or RCD.
- Failed, overloaded or ageing power supply.
- Loose, damaged or oxidized cables and terminals.
- Moisture inside the enclosure, corrosion or secondary-side short circuit.
- Faulty timer, photocell, relay, controller or local LED modules.
Safe checks
- Check the normal switch.
- Check whether the breaker or RCD has tripped.
- Check an external timer if accessible without opening the sign.
- See whether other equipment on the same circuit has power.
- Take photos of the full sign and the dark area.
- Photograph the power supply label only if it is safely visible without touching wiring.
When it is urgent
- Breaker or RCD trips repeatedly.
- Burning smell, sparks, crackling or strong heat.
- Water inside the cabinet, damaged cable or exposed conductors.
- Failure after rain, snow, lightning or a voltage surge.
- Inspection would require opening the cabinet or working at height.
How PixelRing proceeds
- We identify whether the whole sign or only one zone is affected.
- We check feed, breaker, power supply, controls and output voltage.
- We inspect cables, terminals, polarity, moisture and LED modules.
- We repair the cause rather than replacing the first suspicious part.
What affects scope
- Mounting height and access.
- Power supply position and accessibility.
- Sign size, number of letters and sections.
- Condition of cables, enclosure, seals and controls.
- Need for partial disassembly or sealing work.