Radio expert wanted!

[luggsey]

If the op can get audio through his CD and CD and tuner are separate inputs to his amp can he possible swap digital Inputs at the amp to narrow down the fault?

[Floodys]

Pmsl! Many thanks..... As said before its trying to get ones head around that a tuner is in the boot in the roof.... Considering nearly all older and maybe current cars have a standard "aerial" then the front head unit has the cd, tuner, all built in. Now that you've cleared it up for me and I'm eternally grateful for all your help and to others that may have the same problem I'll be off now and have a fiddle around with the audio system. Fingers crossed I'll sort something if not will put up with the click or just play CD's all the time. Once again many thanks for the time you have spent helping. Without people like yourselves with all the knowledge XC owners would be broke!
Same go's for a lot of Peugeot 205 gti owners out there as that my field of expertise as I've had them for 20 years plus and I have lots of people come to me with various questions on a daily basis that I can answer ASAP due to having them so long!
Many thanks again....

[Floodys]

Originally Posted by luggsey

If the op can get audio through his CD and CD and tuner are separate inputs to his amp can he possible swap digital Inputs at the amp to narrow down the fault?

I thought that, I noticed yesterday you can swap the fibre optic cable between the MD and the CD, today I may see if I can pop out the "radio" optic leads and swap for either MD or CD.
One would think that will eliminate the amp?

[SwissXC90]

Originally Posted by luggsey

If the op can get audio through his CD and CD and tuner are separate inputs to his amp can he possible swap digital Inputs at the amp to narrow down the fault?

Yes, this is how you do it:
1. Build a MOST fiber device to receive and decode the MOST signal
2. Identify the IDs of the desired audio channels
3. Swap the IDs over
4. Reconstruct the MOST signal and output it

You will need:
Electronics experience
Hardware design experience
Microcontroller design experience
Software design experience
MOST experience
A test environment
A manufacturing facility

So not impossible, but not really something you can do at home....

[SwissXC90]

Originally Posted by Floodys

I thought that, I noticed yesterday you can swap the fibre optic cable between the MD and the CD, today I may see if I can pop out the "radio" optic leads and swap for either MD or CD.
One would think that will eliminate the amp?

You appear to forget that it is a unidirectional fiber ring.

You can disconnect the tuner and bridge the optical leads together with a fiber loop. But of course you lose all radio functionality.
And the system may not work when one of the key components is not present in the ring.

A tuner is always present, and it is not expected that the tuner will be missing.
A MD player and a CD player were optional, and are allowed to be missing from the ring.
Likewise the subwoofer, phone and nav are also optional, and can thus be bridged without any impact

But the ICM, the amplifier and the tuner form the minimum 3 components you must have present for normal operations.

[luggsey]

Originally Posted by SwissXC90

Yes, this is how you do it:
1. Build a MOST fiber device to receive and decode the MOST signal
2. Identify the IDs of the desired audio channels
3. Swap the IDs over
4. Reconstruct the MOST signal and output it

You will need:
Electronics experience
Hardware design experience
Microcontroller design experience
Software design experience
MOST experience
A test environment
A manufacturing facility

So not impossible, but not really something you can do at home....

So no separate digital signals, all combined and networked?

[SwissXC90]

Originally Posted by luggsey

So no separate digital signals, all combined and networked?

The MOST bus contains multiple parallel audio signals (and video if you want) all at the same time on the same fiber. They are logically separate, but physically on the same fiber.

The Volvo XC90 contains the following audio channels on the MOST bus, on the same fiber, all running at the same time:

• AM/FM Radio
• CD
• Minidisc
• AUX
• Satellite radio (in the USA)
• Phone
• Microphone (yes, a separate channel)
• Subwoofer
• Nav
• (and maybe more, what have I forgotten?)

Yes, even the phone microphone travels as a separate channel on the MOST bus from the AUD amplifier around the ring to the PHM phone module.

They are all logical channels, not physical channels
Physically, the MOST ring is a single fiber optic cable.
The specification allows for up to 64 devices to be present.

[SwissXC90]

From the MOST specifications, the standard functional blocks in a MOST ring are:

• NetworkMaster
• ConnectionMaster
• Vehicle interface for vehicle related data
• Diagnosis – access to diagnostic functions
• EnhancedTestability – necessary for compliance tests
• AudioAmplifier
• AuxIn – interface to mobile consumer electronic devices like memory sticks
• MicrophoneInput – interface for microphones
• AudioTapePlayer – tape decks
• AudioDiskPlayer – CD player or CD changer
• DVDVideoPlayer – DVD player
• AmFmTuner – radio tuner
• TMCTuner – trafic information (Traffic Message Channel) signals
• TVTuner
• DABTuner – digital radio (Digital Audio Broadcast)
• Telephone – interface to mobile telephone
• GeneralPhonebook – phonebook of a telephone receivers
• SDARS – tuner for Satellite Digital Audio Radio Service
• NavigationSystem – navigation unit
• GraphicDisplay – display unit

Multiple devices of the same type can exist, they need to be assigned different addresses to uniquely identify them

So readers of this thread should now have a small overview of the complexities of a MOST system and how remotely removed it is from the "old school" analogue audio systems that were connected together by copper wire (and had all the associated noise, interference and ground loop problems...)

Indeed, repairing a MOST system without a test bed to test devices means that you are basically limited to module replacement only.

And that is what the Volvo garages do: they replace faulty modules with new modules.

[Moose Test]

Originally Posted by SwissXC90

Yes, with a proper VIDA dealer registration.
You have to purchase the software application to disable the security, so it's a dealer only software update.

Correct. Once the audio security is disabled, the serial number check no longer takes place. You can replace any audio system component.

Does anyone have any first hand experience with having a UK dealer agree to do this for them? I believe I have read in other posts on this forum that dealers consider this "diagnostic" (allows them to swap out modules with known good ones for testing purposes) but insist that security is restored before the vehicle is returned to the customer.

[Floodys]

Quick update for anyone who's interested, I'll probably get shot down for this but I'm 99% sure I've narrowed it down to the amp as Swiss had mentioned one of a couple of parts, the way I worked this out was interesting..... I had all the roof aerial, reliever, sat nav aerial etc etc apart and eliminated the big panel aerial as I disconnected it and still had the click, same for sat nav module, booster module. I then thought about what another posted had said re using another part of the loop ie put the radio receiver/tuner or whatever you want to call it in place of the MD or CD up front.... I managed to prize out the optic leads at rear of car where they would plug into the reciver and bridge them together via a piece of rubber washer hose so that the optic light could see each other! I then managed to pop out the optic leads at the MD player and place them in the radio reciver lump, gave it a 12v and a neg and fired it all up, sure enough no click... This would also eliminate the ICM display bit at front with the volume button on!
Next question before I either pull the amp apart or go down the road of getting another amp, turning off the security part, if all these components are on the fibre loop and go back to the amp as one in/out fibre, how can it be a fault with the amp if everything is on the same loop? I mean, if I could in theory plug the radio reciver/tuner in place of the MD player then I'd be out of trouble.... But obv I can't as its a massive lump!
BTW the radio was selected as FM, AM etc not MD but radio coming through?