01-08-2012, 12:35 PM
Officially Welcomed to the 'Fest
Location: Chippenham, Wiltshire, UK
Join Date: Jun 2011
Mein Auto: BMW E65 745i
DIY - DVB-T Upgrade Cheap Option!
Hope you have all had a good xmas and new year!
As most of you know if you have the old analogue TV tuner in the UK its almost now 100% useless! and upgrading to the BMW hybrid version can be expensive if you can get hold of one!!!
I will explain here what I did to convert my old analogue tuner to digital.
This is my set-up as it stands:
The tuner I used was an Eonon V0012, it's a cheap chinese unit found on ebay from anything between £70 - 100, to be honest the quality is not bad, even when dissecting the unit out of curiosity I was surprised at the overall manufacturing quality and board layout.
Anyway anything will suffice, a more expensive Alpine unit would have been nice etc... depends on your budget.
Right, there are pros and cons to this setup. Pros being its a cheap alternative, you can listen to digital radio etc.... the con being the channels cannot be changed from the iDrive or steering wheel (yet!).
To perform this upgrade you MUST have the factory fitted analogue TV module in the boot! basically the TV module has a CVBS video output (yellow plug on many TV and DVD platers etc) this is easy, this signal is sent directly to the sat nav computer where it is scaled and converted to RGB and then sent to the control display in the dashboard.
The audio is a little more tricky! the E65 has the fibre optic MOST bus, all audio is converted to digital and split into packets and sent around the fibre loop until it reaches the ASK or Logic 7 amp where its extracted, converted back to analogue and blasted out of the speakers!
Below is a picture of the standard TV unit with the cover removed:
Most of the board is the power supply, MOST interface circuitry and a processor that controls the tuner module itself (vertical shielded box).
On teh rear of the board almost directly under the MOST bus interface circuit is a 14 pin SOIC marked PCM1801U. This is the IC that converts the analogue audio to digital.
The tuner itself only outputs MONO audio, therefore Left and Right channels need to be joined together, I simply joined both channels with resistors and connected to the 1uF capacitor on the board.
The 1uF cap is lifted from the PCB and placed on the little mod board and then linked back down to the pad that connects to pin 1 of the PCM1801U.
The grounds are also joined together and soldered to a common ground on the PCB.
The TV module now modified with 'aux' input. when 'VIDEO' is selected on the iDrive the audio from the TV module is now output through the car speakers.
Another tricky problem is powering the new tuner on and off without it interfering with the power management module in the boot!
I designed and built the circuit below:
Basically it has a permanent 12V from terminal 30 in the rear fuse box, the ACC line of the new tuner is switched on using a P-Channel mosfet, the gate of the mosfet is pulled high to switch it off and to GND to switch it on, unfortunately the opposite way we want! hence the need for another smaller N-Channel mosfet, this takes a signal from the power management unit (pin 18 of the 37 way connector) this input (to switch the tuner on and off) is switched high whenever the key is in the ignition.
A constant 12V is also fed to the tuner via terminal 30, there is negligible current draw on this input so the car will go to sleep as normal.
pictures of rear fuse box with the two extra fuses(top right) and the blue wire switching the power on and off to the new tuner.
Grounds connected to stud of comb connector:
Thats it really, if anyone wants schematics of how its wired then let me know, hope this may of be some use to someone!