LNB Burnout: Power Issues That Kill LNBs

“LNB burnout” is the sudden death of an LNB, usually caused by a power problem rather than weather. It is dramatic — one moment you have a picture, the next moment you do not — and it is often preventable.

What Is LNB Burnout?

The front-end amplifier in an LNB is delicate. A voltage spike, an overvoltage, or a reverse-voltage connection can destroy its semiconductor inputs instantly. The LNB then goes silent completely — no signal, no strength, nothing.

Common Causes

1. Lightning surge

The big one. A nearby strike induces thousands of volts in the coax. Even without a direct hit, the induced surge can kill the LNB. A surge protector on the cable helps.

2. Two receivers fighting

If you split one LNB output to feed two receivers, both try to supply 13/18 V. The conflicting voltages can damage the output stage. Always use a multi-output LNB, not a splitter.

3. Faulty receiver power supply

A failing receiver supply can overvoltage the LNB output. If you have burned out two LNBs in a year, suspect the receiver.

4. Mishandling during fitting

Shorting the centre pin to the braid while the receiver is powered can pop the LNB input. Make connections with the receiver unplugged.

Symptoms of Burnout

• Sudden total loss of all signal (not half channels — all channels).
• Receiver reports “no signal” or “short circuit”.
• Voltage present at the LNB end but no signal returned.
• A burning smell if you unscrew the connector.

Preventing Burnout

• Fit a coaxial surge protector between dish and receiver.
• Never split a single LNB output.
• Disconnect the LNB cable before doing anything inside the receiver.
• Keep a cheap multimeter in the toolbox.

What to Do After a Burnout

Replace the LNB, but also check the receiver — if the receiver caused the burnout, the new LNB will die too. If you have had two failures, get the receiver's power supply checked.

LNB burnout is sudden and annoying, but usually cheap to fix. A €10 surge protector and a habit of disconnecting power before working on connectors prevents most cases.