Symptoms
- Soundbar shows an optical input signal but no sound plays
- Sound works over other connections (HDMI, Bluetooth) but not optical
- Sound is present but distorted or cutting in and out
- No signal detected at all on the optical input
Likely causes
- CommonTV's digital audio output set to an incompatible format (e.g., Dolby Digital Plus over a connection that only supports standard PCM/Dolby Digital)Optical cables have limited bandwidth and can't carry every modern audio format.
- CommonTV audio output not set to 'optical' or 'digital'Some TVs default audio output elsewhere and need this manually selected.
- PossibleOptical cable not fully seated or has a damaged fiber insideOptical cables are fragile internally and can fail if bent too sharply or if the connector isn't fully inserted.
- PossibleDust or debris blocking the optical portA blocked port can prevent the light signal from transmitting properly.
- Less commonFailing optical transmitter or receiver in one of the devicesAn internal fault on either end will prevent any signal from passing.
What to do
- In the TV's sound settings, change the digital audio output format to 'PCM' or 'Dolby Digital' (not 'Dolby Digital Plus' or 'Auto' if issues persist), since optical has bandwidth limits.
- Confirm the TV's audio output is set to 'optical' or 'digital audio out' rather than internal speakers.
- Remove and firmly reinsert the optical cable at both ends, listening/looking for it to click or seat fully.
- Check both optical ports for dust and gently clean with a dry cotton swab if needed.
- Try a different optical cable, since internal fiber damage from tight bends is common and not visible from outside.
- Test the optical connection with a different source device if possible to isolate which end has the fault.
Tools and parts
- Cotton swab
Optical audio cableSearch: “toslink optical audio cable”
When to call a pro
If no combination of settings or cables produces sound, one of the optical ports likely has a hardware fault and the device may need professional repair.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.