A2 aerial connector confusion

ajsellors said:
Hi,

I can check the wiring tomorrow night and report back.

Two other things to check in the mean time:

Has the head unit been coded correctly for the Diversity unit?
http://wiki.ross-tech.com/wiki/index.php/Audi_Radio_Generation_II

Is the earth on the tailgate OK?
The amps in the tailgate use the earth of the tailgate frame to complete the power circuit. The earth wire to the tailgate can fray with opening and closing causing bad radio reception.
Try a jump lead between the battery negative and something on the tailgate.

regards

Andrew
Click to expand...
Hi thank you so much, I will try checking the tailgate is earthed.

So are you saying there is more electronics after the diversity amp? I see there are two double coax connectors going into the amp, I assumed these wires go to discrete aerials that ha e no actual electronics and are passive?

I don’t know if the new diversity amp is working or not as I still don’t get radio reception. It’s even casting doubt on whether the powerd connector at the radio end goes to the right one at the amp end. I think it’s right but as I said I can see someone has rejoined the connectors at the radio end suggesting the radio must have been stolen once and the theif cut the coaxes. Therefor it also can’t be the original radio. I also wondered whether I have the right radio for the car, as the one I have has the code written on it as if it was once on a shelf to be sold. So I’m guessing it’s secondhand.
 
ps. Just clicked on that link following your question as to whether my radio is coded correctly for diversity, it looks interesting and although I am technical minded, I need a clue as to what all that relates to please as I don’t quite understand.
 
gregjames67 said:
ps. Just clicked on that link following your question as to whether my radio is coded correctly for diversity, it looks interesting and although I am technical minded, I need a clue as to what all that relates to please as I don’t quite understand.
Click to expand...
Hi,

I have no idea of your level of expertise so forgive me if I assume you know nothing, a bit like me!:oops:.

I had a quick look at the link and it relates to the use one small part of VCDS. VCDS is an expensive bit of software, vendor Ross-Tech, that is the bee's knees diagnostic tool for use on our A2's. I do have a little background in computers and it looks to me the adaption process is ultimately storing a binary bit pattern in the memory of the radio to control various functions. The binary bit of interest to you is 'diversity installed', I.e bit=0 diversity unit not installed, bit=1 diversity installed. If this bit is not set set then the radio does not know a diversity unit is installed then it simply will not try to to use it, but bear in mind I could be talking cobblers.

To be honest I would engage the expert services of Tom(Timmus) to fix it all. PM Tom to arrange a visit, problem sorted.

Hope this helps.

Andy
 
gregjames67 said:
Hi thank you so much, I will try checking the tailgate is earthed.

So are you saying there is more electronics after the diversity amp? I see there are two double coax connectors going into the amp, I assumed these wires go to discrete aerials that ha e no actual electronics and are passive?

I don’t know if the new diversity amp is working or not as I still don’t get radio reception. It’s even casting doubt on whether the powerd connector at the radio end goes to the right one at the amp end. I think it’s right but as I said I can see someone has rejoined the connectors at the radio end suggesting the radio must have been stolen once and the theif cut the coaxes. Therefor it also can’t be the original radio. I also wondered whether I have the right radio for the car, as the one I have has the code written on it as if it was once on a shelf to be sold. So I’m guessing it’s secondhand.
Click to expand...

Hi,

sorry, I was caught up at work today so won't have time to check this. I will do it tomorrow.
The wires from the head unit go straight to the diversity unit without interruption. Each antenna in the tailgate is connected directly to a small amplifier. These are located behind the trims on the side of the glass and under the main lower piece. Without the diversity unit the head unit connects direct to the amp in the tailgate but with diversity there are multiple amps and aerial elements in use. 4 to be precise, as per the 4 feeds from the small connectors. The diversity unit switches between aerials depending on frequency and signal strength to give the best reception.

The amps in the tailgate get power +ve from the central core of the coax but the earth comes through the metal of the tailgate itself. If the tailgate earth is on the way out then the amps don't get enough volts to run properly and signal strength is low. A tell tail sign that the earth lead is on the way out is that the reception gets worse when the rear window heater is turned on.

Pictures of some amps in tailgate:

DSC04768.jpg
DSC04767.jpg


Note that removing the diversity unit completely and connecting the head unit directly to the amps in the tailgate doesn't work. I fixed another member's lack of radio reception by reconnecting their diversity unit. All 6 wires from the head unit and aerial amps had been pulled out of the plugs and twisted together!

Regarding the head unit, like many of the computerised modules in the car, it has a set of configurable options so that the same unit can be used in different environment such as number of speakers, external controls on the steering wheel etc. Its therefore important that the correct functions are turned on (and off) to match what is present in the car. As things have obviously been messed with in the past its possible that the diversity function may have been turned off in the head unit or even its a head unit that was originally in another car that didn't have that function.
To read and adjust the settings you need an interface that that can communicate with the modules in the car. VCDS is a popular interface which allows a laptop to communicate with the car and is probably the most functional but also now very expensive. Cheaper options exist but their abilities vary. The cheapest way is to have someone else who has an interface help you!

regards

Andrew
 
Note that I have the VCDS cable if you are ever traveling though Hampshire then i'm in Alton and would be happy to help.
 
I would dearly like to fixall these niggles with mycar. The Diversity issue is doing my head in. I suspect that I do not have the original radio as the coax wires at some point have been cut and resoldered back on plus my radio has writing on it with codes so I suspect it was sold secondhand. Perhaps I don't have the right codes in the radio??? If I came to yours hae you the cable and software to interrogate and change the settings? That would be awesome! Greg
 
And the answer is:

The yellow connector at the head unit end goes to the yellow connector at the diversity box
The black connector at the head unit end goes to the white connector at the diversity box.

Andrew
 
ajsellors said:
And the answer is:

The yellow connector at the head unit end goes to the yellow connector at the diversity box
The black connector at the head unit end goes to the white connector at the diversity box.

Andrew
Click to expand...
Crikey okay well my square orange at the radio end goes to the white and the diversity end.

My black round at radio end goes to the orange at the diversity end. I will double check in a mo but that sounds bad already.

Really appreciate you checking for me mate
 
Some GOOD NEWS :0)!!!With my new diversity unit in place and the coax wires swapped around so the little square orange goes to Orange input and 12v goes to white input, I have good radio reception.... for a few seconds!!! Then after I’d finished pumping the air, the radio fell silent. I thought my diversity had worked and then blown.

I replugged it all back in bit by bit and I have discovered that I need to leave out one of the 4 aerial coax cables (which go in as twins into double coax sockets). The left twin plug has two coax in it, one of them has a white sticker, the other a blue sticker. The white one is killing the reception. So for now if I just keep the three going into the diversity and the white labelled one out, it all appears to work fine. There must be something wrong with the white aerial of the 4?? I don’t know where the white one hides so for now I will leave it unplugged and run on three
 
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