silkworm

Hi,

I know most of you are from US and your Audi cars don't have a factory-fitted TV-tuner because that's not allowed, but this is a great forum and some of you might be able to help me anyway.

I recently bought a hybrid TV tuner from ebay. I already had the analog TV tuner fitted and I just swapped it with the new TV tuner.

Everything seemed right at first - TV reception was great, image was sharp, I managed to connect the VCDS and could diagnose the tuner, there were no errors.

But then, after 20 to 30 minutes, the TV tuner doesn't function properly anymore, or at least that's what it seems.

The image is still fine, but I cannot change the channel (actually I can select a new channel but it reverts back to the old selected channel) and it seems that it's a problem in the MOST system, because the sound keeps interrupting (even if I change the source to radio or CD-changer), and a relay in the trunk keeps clicking as if the MOST system was disconnected. If I try to shut down MMI by long pressing the mute button, then the screen turns off but it retracts itself after a couple of minutes. VCDS either refuses to connect or is dropping the connection during this time. If I disconnect the MOST cable from the TV tuner and connect a loop/bypass connector, then everything works fine (except for the TV tuner of course) and the relay doesn't click anymore.

If I disconnect the tuner completely and give it some time (to cool down perhaps), then it works very well for another half an hour (good reception, clear image, I can diagnose it with VCDS) and after that the problem comes back. The tuner has the latest software version. I also put a different head unit and the problems is still there. I even disconnected the AMI but without any changes.

VCDS won't give me any error to the MOST bus, but while that relay clicks, I can't connect to any device that uses the MOST ring, except for the CAN gateway. I repeat: if I disconnect the TV tuner from the MOST ring, then immediately every device turns back to life (radio, AMI and CD can play uninterrupted, the sound quality is good and these devices can be diagnosed again).

Did I buy a faulty TV tuner or is there something else that I'm missing?

Giovanni Giovino 6.0+6.0TT

I think so.

Jack88

Does the unit feel particularly warm after running it?

schiu

Sounds like the cooling fan of the tv tuner is faulty. You can run an output test of the fan using the vcds

silkworm

On the contrary, the fan goes on like crazy when that click happens.
I already ran the output tests and everything was working well: antennas, video/audio signal and even the fan. I attached a picture with a diagnose screen which is shown on the MMI display when I access the TV tuner module with VCDS (yes, I know the FAN shows 0 but that's only because the FAN wasn't yet turned on when the picture was taken).

I can't tell... the unit feels warmer but it's doesn't seem to run hot. However, as I specified above, when the problem happens, the fan is 'running wild', but if I disconnect the MOST connector, eventually the FAN stops as the unit gets cooler. If I reconnect the MOST connector, it performs well for a short period of time (much shorter than the initial period of 20-30 minutes) but then the problems comes back.

At first, I thought it was a compatibility problem, but then I saw that the antennas and connectors/pinouts are the same as for the analog TV tuner.

Jack88

Is there any buildup of dust or anything otherwise impeding airflow for the fan? I'd be tempted to disassemble the unit a bit and look for anything out of place. It sounds like the software is fine but may you have some sort of hardware issue. Poor connection, something loose, buildup of some kind, etc. My thoughts, anyway, this isn't in my experience, so I'm guessing.

silkworm

I thought of that, but I don't want to disassemble the TV tuner because I may return it to the seller. I didn' talk to it about this yet, because I want to be sure that the unit is indeed defective.

I examined the fan from the outside and it seems to be perfectly clean, as if someone cleaned it recently. Normally I would suspect that someone else already opened the unit, but I know that a fan like this can be cleaned well with compressed air spray and a smooth paint brush.

I tried to swap the position in the MOST ring with that of the NAV unit. I was sure this wouldn't solve the problem (and it didn't) but after the short time (~ 20 seconds) in which the tuner was disconnected from the MOST ring, all devices worked well for a minute or two after plugging back the MOST connectors, then the problem came back again.

It think the tuner goes out of sync with the other devices and transmits through the fiber optic cable slower or faster than the other units and they can't keep up. A temporary disconnection of the fiber optic may reset the tuner back in sync for a short time.

I thought there is a bad coding because I didn't found any information about proper coding the hybrid TV tuner, but it seems to be the same as the coding for the analog TV tuner.

I'll do some more experiments and keep you posted.

silkworm

I monitored the TV tuner further, because I was sure that the problem manifests when the fan was turned on (as if it was taking too much current and overloads the circuit). I was again wrong.

Meanwhile I borrowed another Hybrid tuner from someone, which is working fine. I think the unit I bought is really defective. It's time to talk to the seller.

yysnet

Did you get anything back from the seller? I would like to buy the defective unit as I need a RF head...

CHeers

Giovanni Giovino 6.0+6.0TT

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