In this guide
No sound through an optical cable is almost always caused by the TV audio output being set to the wrong format, a loose or damaged cable, or HDMI ARC overriding the optical output. Switching your TV audio output to PCM and checking the physical connection fixes it in most cases.
- TV audio output is set to PCM (not Dolby Digital or Auto)
- Cable is fully inserted and the red light glows at the connector
- Receiver or soundbar is set to optical input mode
- TV internal speakers are disabled
- HDMI ARC/eARC is active and has disabled the optical output
- Cable is bent, cracked, or not seated all the way
- Receiver is not switched to the correct optical input
- Power-saving mode is cutting the signal during silence
Step 1: Check the Audio Format Setting
The single most common cause of no sound through an optical cable is an incompatible audio format. Optical cables can carry PCM stereo and basic Dolby Digital or DTS, but many TVs default to a format the receiver cannot decode.
Go to Settings > Sound > Expert Settings > Digital Output Audio (menu names vary by brand) and change the output to PCM. If you were on Auto or Dolby Digital, this change alone will restore audio in most cases.
Step 2: Check the Physical Connection
Optical connectors have a protective cap — make sure it has been removed from both ends. Push each connector in firmly until it clicks. Look for a faint red glow inside the cable at each end; no glow means no signal is being sent.
- Connect to TV AUDIO OUT (OPTICAL) and receiver AUDIO IN — not the other way around.
- Try a different optical cable to rule out a damaged or bent fibre.
- Inspect both ports for dust or debris and blow them out gently.
For a broader look at troubleshooting digital audio connections, Sony’s optical audio support guide covers common failure points across many device types.
Step 3: Check for HDMI ARC Conflict
If your TV is connected to an AV receiver or soundbar via HDMI ARC or eARC at the same time as an optical cable, the TV will typically disable the optical output automatically. You cannot use both simultaneously on most TVs.
Disconnect the HDMI ARC cable and test optical audio again. If sound returns, you need to choose one connection method. HDMI ARC carries more audio formats, but optical is fine for PCM stereo and standard surround.
Step 4: Select the Right Input on Your Receiver
Your receiver or soundbar must be set to the correct optical input. Use its remote to cycle through inputs until you reach Optical or Digital In. Also confirm the volume is not muted or set very low on the receiver itself, not just the TV.
Quick Reference Table
| Setup | Works? | Need | Note |
|---|---|---|---|
| TV optical to soundbar | Yes | PCM or Dolby Digital output | Disable HDMI ARC if also connected |
| TV optical + HDMI ARC both active | No | One connection only | ARC disables optical on most TVs |
| PC optical to receiver | Yes | PCM output, power-saving off | Power-saving can drop signal during silence |
| Damaged or bent cable | No | Replacement cable | No red glow = no signal |
If you are also dealing with video connection issues, see our guides on why USB-C to HDMI is not working and whether USB-C can connect to HDMI for related troubleshooting steps.
Bottom line: No sound through an optical cable is almost always a settings or connection issue, not a hardware failure. Set your TV to PCM output, confirm the cable glows red, disable HDMI ARC if it is also connected, and select the optical input on your receiver — and audio should return immediately.