Know how to test your DTH LNB, identify polarity issues, and fix common “No Signal” problems.
What is DTH LNB??
The LNB (Low Noise Block Downconverter) used on your Dish antenna is the main equipment to receive the signal from your satellite dish and convert it for your set-top box. If your LNB is dead or not working, then you will not receive a satellite TV signal on your set-top box. Here we will let you know that How do you know if your LNB is bad.
Here is a very simple trick to check whether your LNB is faulty or not. So, if you are not getting a signal on your Set-Top Box, just remove the coaxial cable from your set-top box and see what changes come in the signal and strength bar, which is shown by pressing the “Info” button in your satellite receiver.
And let’s understand by case –
Case 1: Signal Strength 50–99% but Quality = 0% –
It means the box is definitely connected to the LNB and receiving RF energy, but it cannot lock onto a valid satellite signal.
Reason –
- The receiver may be tuned to a frequency that doesn’t match your satellite provider
- The dish is pointed in the wrong direction or slightly off the satellite.
- Trees, buildings, or even a dirty dish surface can block or scatter the signal
- The LNB may amplify noise instead of a clean signal, or the cable may be damaged.
- Wrong LNB type, frequency, or DiSEqC port selected in the receiver menu
Case 2: Signal Quality = 99% but Strength = 0% –
Signal Strength is meant to show the raw RF level coming from the LNB. Signal Quality shows how well the receiver is locking onto the satellite (SNR/BER). You cannot have 0% strength and 99% quality at the same time, because quality depends on having usable RF power. So it will not be possible technically or maybe Receiver Bug or Mislabeling of signal info.
Case 3: LNB Power = 100% but Strength & Quality = 0% –
Your set‑top box is successfully sending DC voltage (13V/18V) to the LNB, which means the LNB is okay. But no RF signal is being detected from the LNB. You need to set your dish antenna.
Case 4: Only H or V Frequencies Work –
If your system is showing signal only on H (Horizontal) frequencies but not on V (Vertical) frequencies, or vice‑versa, that points directly to a polarity switching problem.
Satellite LNBs switch between polarisations based on the DC voltage supplied by the set‑top box:
13V DC → Vertical polarization
18V DC → Horizontal polarization
If one polarity works and the other doesn’t:
The receiver may not be sending the correct voltage for that polarity.
The coaxial cable or connectors could be damaged, causing a voltage drop.
The LNB itself may have partially failed — it’s common for one polarity to stop working first.
FAQs –
How can I solve the Tata Sky no signal?
You can check Tata Sky Set-Top Box signal settings from here.
