Sign acting up? Let's figure out which part failed.

Answer a few quick questions and we'll pinpoint the likely faulty component. Works for any sign — we'll show the NovaStar-equivalent part, so just match it to the model inside yours.

Heads up: the next steps assume you, or a contractor, can safely access the sign to complete them.

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Support tip

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How to open the sign & reach the cards

Where to look: the two boxed modules near the bottom sit in front of the electronics — remove the left module to reach the controller (TB20), and the right module to reach the MRV receiving card.

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Applies to signs purchased after 2020 (X Series modules).

Where the controller and cards sit

Example: a sign 6 modules wide × 3 tall, seen from the front. Each square is one module — the controller and receiving card sit behind the two marked modules, so those are the ones you remove.

Controller (TB20) — behind the bottom-left module

Receiving card — bottom row, 2nd module of each section

1 — Open the bottom-left two modules

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✕ unplug this cable

Bottom-left corner of the sign, seen from the front. The TB20 controller sits behind the first module and the MRV receiving card behind the second.

To remove each module: insert a 3mm hex key into the two lock points on the module face and turn counterclockwise, then lift the module out and unclip its power cable, ribbon cable and safety hook.

▶Watch: removing & reinstalling a module▾

Removing a module

Reinstalling a module

2 — Unplug the TB20 cable from port #1 on the MRV

TB20 controller

MRV receiving card

1unplug

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3 — Press the TEST button on the MRV twice

The TEST button is boxed in orange, next to the network ports. A healthy card lights its section with a test pattern.

The two modules you opened

TB20

MRV · port 1

new cable

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Which app are you using?

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Heads up: the next steps assume you, or a contractor, can safely access the sign to complete them.

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Modules wide (columns) Modules tall (rows)

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Controller (TB20) + PoE adapter — bottom-left module, first section only

Receiving card (MRV) + its RS-15 supply — bottom row, 2nd module of each section

Continue

Heads up: the next steps assume you, or a contractor, can safely access the sign to complete them.

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Viewed from the front — left is left. Dark tiles marked: {{ darkCount }}{{ dblNote }}

Show me where to look

Likely diagnosis

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Quick check: {{ logicNote }}

Your sign — {{ gw }} wide × {{ gh }} tall, as you marked it. Each module outlined in yellow hides the HSP 300-5 that feeds a fully dark power zone.

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Built as {{ sectionCount }} section{{ sectionPlural }} (yellow seams) — the same split as our Assembly Planner. Power zones never cross a seam.

Dark tiles you marked Controller (TB20) + PoE adapter Receiving card (MRV) + RS-15 supply, per section Check 1 — remove this module; the failed power supply sits behind it Check 2 — supply for a partly dark zone; test 5V here before replacing the module

Whole section dark ({{ mrvList }}): when every module in a section is out, it is the receiving card for that section or its RS-15 supply / data cable — not the module supplies. Both the card and its RS-15 sit behind the yellow square. Disconnect the data cable and press the card's test button: if it lights the section, replace the cable; if not, meter the RS-15 beside it (no light or under 5V DC = replace the RS-15), otherwise replace the card.
Power supply: every module in zone{{ colPlural }} {{ colList }} is dark, so that zone's supply has dropped. Order {{ psuQtyLabel }} unless a field check shows otherwise.
Two places to check for {{ modList }}: other modules on the same supply are still lit, so most likely the module itself or its ribbon / power cable. But first put a meter on the supply behind the amber tile ({{ maybeList }}) — if it reads under 5V DC, it is the supply; if 5V is good, replace the module.

Zones: within each section, the bottom 3 modules of a column share one supply behind the middle module; a top row is fed in pairs. Our builds couple a maximum of 3 modules to one supply. If your sign was assembled from different section sizes than shown, the supply sits one module up or down from the highlight — check both.

Your sign — {{ gw }} wide × {{ gh }} tall, built as {{ sectionCount }} section{{ sectionPlural }}. Tap any section to switch it on or off — the diagnosis updates as you go. The module outlined in yellow is the one to remove — the card to check sits behind it.

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Signal chain

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Signal enters at A and runs section to section in this order — a red arrow marks the break. Power runs (one breaker feed each, jumpers between stacked sections): {{ runLabel }}. Same layout as our Assembly Planner.

On Off Controller (TB20) Receiving card (MRV) + RS-15 Remove this module — receiving card + RS-15 behind it

Ready to pinpoint the exact part?

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Pinpoint the problem

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Insert a 3mm hex key into the two lock points on the module face and turn counterclockwise, then lift the module out and unclip its cables. Full steps below under "How to open the sign".

▶Watch: removing & reinstalling a module▾

Removing a module

Reinstalling a module

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The receiving card sits behind the module you removed. The TEST button is boxed in orange, beside the network ports labelled 1 and 2. The RS-15 supply is mounted right beside the card.

Troubleshoot · {{ tsKicker }} Previous stepStart over

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Which ports to use

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1leave

2test cable

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1test cable

2unplugged

Port numbers are printed above each Ethernet port on the card. Unplug both cables on {{ front.xLab }} and cable 2 on {{ front.wLab }} first.

Back of the sign

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Order Part

Option 2 — bypass inside the sign

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Modules to remove for the inside route

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View part

Where's the controller on your sign?

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{{ locSecLabel }} TB20 controller (bottom-left module) {{ locMrvLabel }}

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TB20 controller — behind the bottom-left module.

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CPE 210 antenna — mounted outside on the pole, cabled down to the PoE adapter.

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How to open the sign & reach the parts

Signs built after 2020 use the tool-free X Series module — remove a module from the face of the sign to reach the electronics behind it:

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Applies to signs purchased after 2020 (X Series modules).

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{{ p.price }} Order Part

Important — match your exact part. This tool identifies which component has failed, not the brand in your sign. The part shown is the NovaStar equivalent; the same diagnosis applies whether your sign runs Huidu, DBStar or another controller. Because these parts are not cross-brand interchangeable, always order the version and model number that matches the part already inside your sign — if it differs from what's shown, confirm compatibility with us first.

Not 100% sure this is it?

Our techs will confirm the exact part before you buy — free.

Talk to an expert

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This tool suggests the most common cause based on the symptoms you describe. The solutions provided assume that you are, or have contracted, someone who can safely access the sign to carry out the recommendations. Final part confirmation is always available from our support team.