Hey Everyone,

I know this issue has been done to death but I just have a query.

So basically amongst a few jobs to get this TD6 back up to standard was sorting the frozen display screen out.

So today I bypassed all the fibre optical cables and to my amazement the screen came on showing the radio, but unfortunately no sound . It won't allow me to select the CD changer either

My question is that does the amplifier have to be connected to the fibre optics for the sound, obviously I unplugged the white leads out of everything and ringed them all together.

Thanks everyone.

Landrover6176 said:

Hey Everyone,

I know this issue has been done to death but I just have a query.

So basically amongst a few jobs to get this TD6 back up to standard was sorting the frozen display screen out.

So today I bypassed all the fibre optical cables and to my amazement the screen came on showing the radio, but unfortunately no sound . It won't allow me to select the CD changer either

My question is that does the amplifier have to be connected to the fibre optics for the sound, obviously I unplugged the white leads out of everything and ringed them all together.

Thanks everyone.

Click to expand...

I don't really know but I would guess that the fibre optic MOST ring carries the audio.

Thank you Datatek. I'll give that a go.

So connected the amp to the MOST ring. It will allow to select a CD now but still not sound.

Do you have the logic 7 Harmon Kardon?
Does it have the touch screen?

backinblack said:

Do you have the logic 7 Harmon Kardon?
Does it have the touch screen?

Click to expand...

It does have the touch screen and logic 7 Harmon Kardon.

Can't find anything in the older manuals but this is from the 2007-2010 manual, I can't see it being much different other than maybe the security aspect. I reckon you need at lease the IHU, touch screen and amp connected to the MOST.

The components of the complete audio/infotainment system are all connected on the Media Orientated Systems Transport (MOST) ring. The MOST ring is a fibre optic communications bus for multi media applications. Sound and control information is passed around the MOST ring and can be picked up by any of the systems units. For example, sound information is sent from the CD autochanger along the MOST ring and is collected by the audio amplifier which then outputs the sound to the speakers.
MOST technology uses a plastic optical fibre which forms a network connecting the audio and multimedia system components. Each component in the ring is connected to the plastic optical fibre through a device known as a Fibre Optical Transceiver (FOT). Each FOT has two optical connections; one connection is sensitive to light and is the input and the second connection forms the light source and is the output. The system operates by connecting the output from one FOT to the input of another FOT.
The light signals are sent in one direction only and are formed in the following way:
Electrical signals are converted into an electrical current
The current then drives a light emitting diode (LED) in the FOT to produce a high intensity red light
The LED transmits the light through a fibre optic cable
A photo diode in the FOT at the opposite end of the fibre optic cable detects the light.
The following components are connected to the MOST ring:
Integrated Head Unit (IHU)
Touch Screen Display (TSD)
SDARS receiver
TV tuner
Traffic Message Channel (TMC) module
Amplifier
Rear seat entertainment module
Personal telephone integration module
CD autochanger.
The IHU is the timing master for the MOST system. The IHU controls and manages the MOST ring and the system components. It is also responsible for the MOST security system. Each component in the MOST ring has a unique serial number. The component serial number is stored in a registry file in the instrument cluster. If any component serial number is not recognized, the entire audio system will not function.

Thank you very much, I did buy another amp as the original looked water damaged and wasn't producing any red light from the fibre optics port.

The part at the bottom where is says it won't work if the systems doesn't recognise the serial number of a part.

How would you input the serial number into the system?

I'm getting closer , at least the screen is now unfrozen

I think that may be for the later 2007-2010 cars as it says the "the entire audio system will not function" where as your is functioning but with no sound.
You seem to be concentrating on the CD but what about the radio?

From the manual

The gateway function stores a unique serial number for each component in the infotainment system. This new system, known as 'Security on MOST' replaces the radio codes used on previous audio systems.

The radio works tunes into stations etc. Just no audio. .

I'd start by making sure the IHU, touch screen and amp are connected to the MOST.

Amp is all connected, just need to get in and have a look at the touch screen and IHU

From memory, if you've changed a component in the system (the amplifier) then it won't be recognised as a valid unit, and it won't work.
You'll need to have any new components added to the registry for them to function.

MOST is a good system when it works, but the moment it needs replacement components, it becomes a pain as a suitable programming device is needed.

Am I right in saying that if the red light is emitting from the optic wires at the rear then the rest leading up to the IHU and display will be OK?

I think it starts at the IHU and goes round from there

Thank you, I've read somewhere about a micro fuse in the radio module controls sounds too.

It was getting dark quick last night. So I'll have another look today.

Update.

The rear Most module, new AMP is all wired up and sending and transmitting the red optical light. But still no sound. .

Fuses in the glove box are all OK. Is there any other fuses.

Is the new amp a known good one?

Just a ebay one. But could be a broke one

Hard to know what to buy as some are probably busted old ones.

yeah not easy to get a known good one I suppose.