How to Fix a Buzzing TV

The buzz or hum from your TV may be caused by CRT scanning, ground loop, or overmodulation. Below, we’ll help you find the quick fixes for each of these problems, but we strongly recommend you buy a newer TV.

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Jump to: 

• CRT scanning
• Ground loops
• Overmodulation

CRT scanning

This is the least likely cause for TV buzzing, but also the easiest to identify and solve. If you purchased your TV before 2005, there’s about an 80% chance that it’s a cathode ray tube (CRT) model. These are typically curved screens and always massive, clunky, and absurdly heavy televisions that loom ominously in the corner of your grandparent’s house.

The hum from these TVs comes from the tubes’ scanning frequency as they shoot electrons at the screen. The frequency this happens at lies near the upper range of human hearing. This high-pitched tone is inaudible to some, but for those of us used to LCD displays and flatscreens, the whine of a CRT is an annoying relic of the past.

Solution: Buy a newer TV or get less good at hearing.

Ground loops

Ground loops are caused by the difference in electrical potential between different grounding points. A ground loop typically produces a loud, low-frequency buzz when you plug in audio or video components.

If your whole setup is connected, the sound will be constant as power runs to the system and won’t vary based on the images your TV is displaying (an essential distinction between ground loops and overmodulation).

How to fix a TV ground loop

Here’s a troubleshooting procedure to determine what the cause of your ground loop is and what you can do about it:

1. The main culprits are your subwoofer and cable or the satellite box feed at the entrance to your system. Unplug the coaxial cable connected to your subwoofer and determine if the buzz vanishes. If it does, the ground loop is probably coming in through your cable/satellite feed.
2. Reconnect the subwoofer from its input to the receiver’s output and disconnect the offending feed from the outboard box or tuner (disconnect the cable before any splitters).
3. If the hum disappears, the solution is to install an in-line ground isolator. One issue to consider is that transformer-based isolators are universally compatible with analog feeds, but they may interfere with HDTV signals. Check reviews before making your purchase to ensure your system is compatible.
4. If the buzz remains even after you’ve disconnected the TV, you’ll need a ground isolator between the subwoofer and your A/V receiver.
5. Finally, you can test these other procedures if you don’t have access to a ground isolator:
   • Plug the subwoofer into a separate outlet from the rest of your setup.
   • Reverse the AC plug for your A/V receiver or subwoofer. (If this plug is a 3-wire plug, you won’t be able to reverse it.)
   • Connect the chassis screws on your sub and receiver with 14-gauge wire. Then, unscrew the ground loop screw on the back of your subwoofer.

Overmodulation

Overmodulation is a painfully difficult process to translate accurately from telecommunication jargon into layman’s terms. A crude analogy is that overmodulation is like dumping five gallons of water into a single measuring cup—the force of the water getting dumped into the cup exceeds the cup’s ability to contain the fluid.

When a video signal sent to a TV is too strong, it causes distortions in the information being transmitted that manifest in a low buzz of about 60hz. The buzz varies in intensity based upon the onscreen graphics because the sharp edges of a figure correspond to drastic contrasts in signal strength.

How to fix TV overmodulation

When the signal is too strong, it overpowers your cable box or satellite tuner. Despite the techy explanation, overmodulation is relatively easy to overcome and is common with analog TVs receiving digital signals.

• If you’re using a satellite tuner or cable box, each comes equipped with a “modulator.” If it’s poorly manufactured or adjusted incorrectly, it’ll be the source of your buzzing. Placing an attenuator between your box/tuner and the TV will reduce the signal strength that interacts with the TV receiver.
• If this doesn’t work, you should get your box/tuner replaced by your cable or satellite provider.

Final take

It’s not uncommon for older TV sets to experience buzzing, humming, or some other variation of unwanted sound. If you’re noticing this with your TV, it’s possible that either CRT scanning, ground loop, or overmodulation are behind the issue.

We’ve laid out some troubleshooting tips above. But, if none of the tips help, your annoying sound may likely be the cause of an internal problem inside your TV, which requires appliance-repair savvy. Barring that remote possibility, happy viewing.

Buzzing TV FAQ