optical fibre lead

[scottish nutter]

i just got a cheap 5m optical fibre lead so i can connect my ps3 and xbox to my digital amp, this worked fine when i only used a short cable but this long one doesnt work, when i check the end of the cable that goes into the amp there is a red light, what im wondering is if the cable is faulty would i still get the red light or is there just not enough getting through to power the sound?
thanks

 

[MarkTaylor]

Optical doesn't do long distances as well as coax, but 5m isn't all that long, I'd normally have said anything up to around 10-12m should work.

It is possible that the signal is degrading too much due to internal reflections which would still leave you with a red light, but little usable information coming through.

Do you have any other optical devices you could test it with?

Also do try the short cable again to verify that everything else is still working OK.