Volume Knob Fitting & RCA Rework

Hello and welcome to post #15 of my blog on building an in-car computer system.

This post will cover how I mounted & permanently installed the volume control knob system from the previous post, and briefly some further improvements and functionality upgrades.

It should be noted that the black machined knob pictured below was not sold with the kit and was purchased separately from Amazon - you can find it in the "people who bought this item also bought..." section.

As discussed in the previous post the volume control knob is fully functional with the computer; the drivers set up and the led's configured to how i want them. To mount it onto the vehicle, I made a trip to my local electronics store and bought some stainless 25mm M3 screws, anti-vibration washers, M3 nuts and some threaded nylon spacers.

Nylon spacers, though they were not used for this project

The first step of installation was to find a suitable place for installation. Keeping with a more traditional layout I chose to mount the knob on the bezel that surrounds where the head unit was located. There is plenty of clearance behind the panel and running the USB cable was easy.

Unfortunately, M3 was the smallest size screws/washers the store sold, so I was forced to drill out the holes in the PCB to suit the screws.

Back of the PCB before drilling

PCB after drilling

Fortunately, due to the excessive thickness of the PCB doing this did not damage the board or  any circuitry. The next step was to mark and drill the centre hole to mount the shaft of the rotary encoder, checking for clearance around and behind the bezel.

Then the PCB was test fitted to the panel, and the positions marked and drilled for the four centre screws

Centre hole and four holes for the corner holes. Note the distortion in the hole spacing is a result of the curved shape of the bezel; the board was test fitted so that the encoder was parallel with the computer screen and not the bezel

The volume control knob was then fitted to the panel, adjusting for fit to make sure the knob aligned parallel wit the screen.

Rear view of the PCB with USB cable attached

Top view

View before fitting the bezel

It should be noted that there were some slight clearance issues with getting the mute function to work properly with the knob (the knob must be pushed in for it to work). There was too much clearance between the end of the rotary encoder and the inside of the knob, resulting in the bottom of the knob touching the screws and bezel before it could push the button built into the encoder. The solution to this was extremely simple: I inserted a conveniently sized screw inside the knob which acts as a spacer.

Screw inserted into the knob to fix the mute function

Overall, I am very pleased with the functionality of the system. It works as intended and is very responsive. However the glow of the LED knob is somewhat covered. this is not a big issue as light shines from behind the knob in the dark, making it bright enough to find at night but not too bright so as to cause a distraction when driving. 

System with the knob removed to reveal the glowing rotary encoder

In addition to installing the volume knob, I also ran the 4 meter USB 2.0 extension cable from the computer down the passenger side A-pillar, as well as a 5 meter USB3 extension cable along the same route. This USB3 cable runs inside the centre console to the USB3 hub (see post #12) installed on the back of the console. The hub is now fully functional and makes plugging devices such as mice, keyboards and storage much much easier than reaching inside the roof console to connect them. 

Back of centre console with USB3 cable connected

The last main point of work for this post was the reworking of the RCA connectors on the cable which carries the audio signal from the computer to the main and subwoofer amplifiers. I was not satisfied with the quality of the connectors, and they were causing an intermittent signal fault with the audio. New gold plated connectors were installed with the aid of a soldering iron and parts holding tool. 

Exploded view (left) of the new gold plated connectors with an assembled one on the right.

New RCA connectors installed on the car computer

Finished product with volume knob and screen installed. A very clean and almost OEM looking installation.

All in all I am very satisfied with this latest update on the project. Fortunately I did not have to remove the computer for the car to do any of the work above, which was a huge relief. Next on the agenda:

• Software UI improvements
• Fit Auxiliary audio in/USB extension cable
• Set up automatic music playlist synchronization between computer and home library
• Get turn-by-turn offroad navigation software working

Keep reading for addition updates, and as always thanks for reading :)

Hardware Volume Control Knob Configuration and Windows Upgrade

Hello and welcome to post #14 of my blog on building a comprehensive in-car entertainment and navigation system

In this post I'll cover a few major changes that were made to the computer's software, and an important and vital hardware addition.

To start off with, I'll outline the situation with windows. It was deemed necessary to upgrade from windows 8.1 to windows 8.1 pro, because of the extra features and native remote desktop functionality it provides. Achieving this was a huge effort, however, as using the "upgrade" option on the virtual installation disc downloaded from Microsoft didn't work.

Because of this, I had to do a clean install on the computer which resulted in many many hours of effort in re-downloading the drivers (I didn't keep the old ones as I thought I had no need for them) and re-installing them and the applications originally on the car computer, as well as all of the updates for windows. On top of this, I had to manually upgrade to windows 8.1 pro from windows 8 pro as for some reason it would not install the update automatically. 

Once windows was reconfigured and all the drivers and hardware working properly, it was time to address a major usability issue that was outstanding on the computer since its first use.

This is that trying to adjust the volume while driving is extremely difficult. On windows 8.1, the easiest way to change the volume was to bring up the charms menu by swiping from the right side of the screen then tapping settings, then tapping and dragging the volume icon to the desired level. Not ideal at all. A tactile system was needed - ie a volume control knob akin to what almost all conventional car head units have.

To achieve this, I decided on a fully digital solution, rather than simply wiring an in-line volume control knob in series with the recently reworked RCA connection system (see previous post). The advantage of this is the volume can still be remotely adjusted from phones and there is the added redundancy of still being able to adjust the volume using the method outlined above.


After some searching I found this little gem, a rotary encoder based volume control knob that was designed specifically for in-car PC applications. One order from amazon.com and two weeks later and it was delivered to my door.

The unit itself is relatively simple. It connects to the computer via the supplied USB cable and will work with windows out of the box to control the volume without any need for driver installation. While not cheap, the unit seems to be of good quality and is properly and thoughtfully designed.

Turning the glowing knob adjusts the volume, and pushing it mutes all audio. In addition to this, it is backlit with a RGB LED and is able to be set to any color via software downloadable from the manufacturer's website. The blue power LED (see above photo) is also fully dimmable.

However, windows does not support the drivers for the LED control functionality, and manual driver installation was required. The supplied instructions asked me to manually install the drivers using device manager in Windows, however on windows 8.1 pro this proved difficult. 

Windows 8.1 would not let me install drivers that are not digitally signed (the unit comes from a small developer who for one reason or another has not signed his work), so It was necessary to activate the advanced start-up mode in Windows and disable the driver signature enforcement setting. I used this tutorial to achieve this.

However, this caused further complications, as an unknown error was preventing windows from rebooting into advanced start-up mode

This error would appear during restarting right before the PC power-cycled itself, giving me about 1.5 seconds to read it before the screen went black. The PC would then boot up normally into windows after instead of launching advanced start-up. This is an extremely frustrating and potentially dangerous condition as if there was an fault preventing windows from booting advanced start-up would not automatically launch, leaving me little options for recovering the PC.

After consulting my IT professional friend and some forums, I tracked down the cause of the problem. The CSR wireless Bluetooth stack software supplied with my bluetooth dongle was causing a windows C++ runtime error. To fix the problem, I had to uninstall the wireless stack and drivers, launch advanced start-up, disable driver signature enforcement, install the LED control software driver then reinstall the Bluetooth stack and reconfigure the dongle. A lot of work for such an arbitrary error!

Once the drivers were installed, the volume control knob was fully functional.

LED control software

The simple but effective software allows the user to pick any colour or brightness for the volume knob to glow, and control the brightness of the power LED. This only needs to be done once, as the program saves the settings in the unit's on-board micro-controller. Also Included in the software pack is the ability to flash new firmware to the volume control knob.

The unit still needs installing into the car's dashboard next to the screen, and a USB extension cable ran from the computer to the unit. I will do this when I have more time

I'd like to thank my friend once more, without your help I would still be stuck trying to install the driver software for the LED's!

That's it for this post, keep reading for future updates. As always, thanks for reading.

Bluetooth fixes and software improvements

Hello and welcome to post #13 of my blog on building a complete in-car computer system. In this post I will cover various software and hardware changes I have made to improve the performance of the Bluetooth system and various software components.

To start off with, I use the system to wirelessly stream music from my smartphone to the computer via Bluetooth. However from the start this functionality has been glitchy. The audio stream is not smooth an continuous as it should be, rather it stutters and occasionally stops working for lengthy periods.

The cause of this is not fully known as I lack the proper instrumentation to find the source of the problem. However based on the symptoms of the problem it is clear that there is some sort of interference affecting the 2.4ghz wireless Bluetooth signal which results in disrupted commiseration between the smartphone and computer. This could be due to the poor placement of the PCIe wireless communications card on the motherboard (though ASUS had little choice due to the very compact form factor of the board), which is very close to the rear panel and is known is known to be affected by nearby USB3 ports and controllers which run at the same frequency, or possibly EMI or back currents from another source. Another possibility is the dual antenna that came supplied with the motherboard could be faulty. Either way it is not acceptable.

After much deliberation I decided to rectify the problem buy buying a USB Bluetooth 4.0 dongle and disabling the motherboard's on-board Bluetooth. This turned out to be problematic however as there were driver conflicts when installing the new drivers for the dongle. I disabled the on-board Bluetooth in the UEFI BIOS, but despite this the drivers and software suite supplied with the dongle were installing for the on-board Bluetooth. The net result was that the Bluetooth dongle was not recognized by its drivers and the bluetooth utility in the system tray was unable to activate bluetooth due to the on-board Bluetooth being disabled on a hardware level. Uninstalling the drivers and reverting to the default windows drivers did not yield results either. The dongle would be visible to my smartphone but would not connect as windows was not allowing incoming connections.

I made many frustrating attempts to fix this without success. I turned to a friend in the IT consolation industry to help me with the problem. With the aid of remote access via Teamviewer and a patched in data hotspot connection via a smartphone he was able to reconfigure the software and drivers for Bluetooth and restore full Bluetooth functionality to the system, all from sitting at his desk more than 30km away. Needless to say I was  impressed. 

After the bluetooth problem was solved we met in person to fix a few other things. including the the functionality of the FM radio system. The USB tuner dongle I chose is capable of much more than just FM radio, thanks to the powerful RTL232U tuner chip at its core. We installed a DVB-T tuner program on the computer to add the capability of digital TV to the computer. However due to ongoing driver issues and the non-TV optimized antenna on the vehicle this is a work in progress. 

A few other performance tweaks were made. We are planning further software tweaks to improve the ease of use of the system. More updates to follow. I would like to extend a huge thank you to  my friend for helping me with the project. 

As always, thanks for reading :). 

USB3 Hub Installation and rework of audio cable.

Hello and welcome to post #12 of my blog on building an in-car computer entertainment and navigation system. In this post I'll cover the reasons why, and how, I integrated a USB3 hub into my vehicle. I also replaced the signal cable that runs from the computer to the amplifiers. This post will be slightly more brief than the others as I don't consider it a vital part of the build, and I have some catching up to do on other progress that has since been made on the system.

Finished product

The hub I installed is a four port high speed USB3 hub which supports an external power supply as well as power from the host computer. It has four switches to individually power up the USB ports.

Parts List (From eBay):

• USB3 Hub
• USB3 Extension Cable
• 12V-5V Step Down DC-DC Converter

(From local electronics store):

• 2X Round SPST switches (though one of any switch will do)
• Wiring and crimps
• 4X 10mm M2 stainless screws, nuts and vibration-proof locking washers
• Electrical Tape

Tools needed:

• Solder, soldering iron, ect.
• Dremel or die grinder
• Drill
• Marking pens, scribe, rule
• Screw drivers
• Bench grinder
• Pliers, side cutters, ect.

Reasons for fitting the hub:

• Increased potential for charging phones and devices. USB3 supports a maximum current of 900ma though with the use of an external power supply this can be greatly increased
• Ease of access for plugging peripherals into the computer - Plugging in USB mice, keyboards and other interface and/or storage devices is somewhat difficult due to the concealed nature of the computer overhead in the roof console
• Increased transfer speeds for storage operations such as copying movies or TV shows to/from the computer onto storage devices
• Aesthetic appeal

The hub is located on the back of the centre console (the armrest/storage container located between the front seats) and will replace an existing system that I fitted a couple of years ago. The old system had four USB2 ports for charging devices, a cigarette lighter port for light duty power applications and a light for ease of use in dark conditions. In the coming photos the holes for the old components are obvious. The new hub covers these up nicely.

The first step was to isolate the power source to the back of the console then disassemble the back of the console. On my vehicle (GU Nissan Patrol) there are four screws holding the back of the centre console on and a couple more that hold the hinged lid on. All of these were removed to expose the back of the console, then I removed the console back plate from the vehicle and took it to the workshop.

Inside of the console with the old wiring present

I removed all of the old wiring bar the positive and negative connections coming into the system from the battery, then removed the old USB2 ports and cigarette lighter socket.

Back view of the inside of the console. The holes for the old USB2 ports and cigarette lighter are clearly visible. Also note this is a rear view of the finished product, the usb and power input cables are visible at the bottom of the photo.

The next step was to mock up the position and fit of the USB3 hub and design a way to mount it securely to the console. The hub easily disassembled via internal plastic tabs into three main components; the case, the backplate and the circuit board. I started by placing the backplate flush with the console then placing the case on top. It became clear that due to the shape of the centre console and the angled sides of the flat plate some material would need to be removed to ensure a snug fit and to allow the two cables to pass through the left side of the console and into the hub.

Note the angled sides of the plate where the hub has been fitted. Material was removed on the left side to hide the plugs.

I progressively drilled out then sanded away the plastic of the console with a drill and die grinder, regularly checking the fit until I was satisfied that the hub would fit nicely. Once that was complete, the next step was to make sure that the power input and USB3-B type plugs would fit without intersecting the back of the console. USB3-B is the current plug standard for high end smartphones and it incorporates the old USB2-Micro B type plug with a USB-3 micro plug. It became clear that the plug end of the supplied USB3-B cable was too thick to fit properly and was putting stress on the solder joints of the socket on the PCB. To resolve this problem I carefully sanded off the plastic outer casing of the plug end with a bench grinder until the wires and solder joints were exposed. I wrapped the lot in electrical tape to insulate it. I also used the grinder to create a flat face on the power plug as well.

PCB with the modified USB3-B plug inserted.

Once I was satisfied that the plugs would fit properly I carefully inspected the back of the PCB and backplate to find places to drill holes for the mounting screws in places that would not hit the underside of the PCB and cause short circuits. This was slightly tricky as in addition to this the holes must avoid the empty space underneath where the old components were installed in the console. Once I was satisfied I could securely mount the backplate to the console I drilled the holes in both the backplate and console and fastened the M2 screws.

Back view with the backplate mounted and the screws fastened

Moving to the front side the console I applied tape over the screw heads to prevent shorting on the PCB.

Backplate with tape over the screw heads. Note that the two screw holes at the bottom (the console is upside down in this photo) need to be accessed later to fit the console back to the car. Luckily the chamfered edge of the hub made this possible without removing the hub.

I then assembled the power plug by soldering two wires onto it and plugged it into the PCB along with the USB3-B plug, then fitted the PCB to the backplate and case onto the backplate. I trimmed the sides of the two switches on the bench grinder to ensure a snug fit.

The next step was to test the hub for correct function. To do this I used a car battery and an adjustable step-down converter, set to 5V (The standard voltage for all USB interfaces). 

Testing the hub

After I was satisfied the hub was working properly It was time to wire the assembly into the car. The old system I used to power the USB2 hubs used two of the adjustable voltage regulators pictured above stacked on top of each other and wired in parallel, but testing revealed that the current output was insufficient and there was an issue with the two regulators "Fighting" each other for current suply. This was caused by minute voltage  output differences between the two regulators which resulted in a high pitched whining sound coming form both regulators; an interesting phenomenon.  

Old power supply system

  

To rectify this I fitted a sealed high output step down converter that I had as a spare.

On my vehicle there is a convenient plastic rail inside the console which made mounting this very straightforward.

DC-Dc step down converter mounted on plastic rail

Once the converter was mounted I carefully wired the its +12V input wire to the top switch, ensuring the 5V output leads were correctly connected to the hub via the plug I assembled earlier (12V supplied to the hub would probably cause it to explode!). Since there was a second switch left over from the old system I added a LED bar light as an afterthought just so it  would do something.

LED bar light mounted on console

The next step was to do some cable management and run the USB3 extension up one of the pillars and through the roof to the computer.

System powered up with the bar light shining brightly. Note an ashtray goes in the centre of the console but due to my USB3 extension being delayed in the mail I left the USB3 cable hanging out of it until I could fit it. 

The final step was to fit the console back onto where it belongs and do a final current output test if the system using my in-line USB current/voltage monitoring device and a large load. The system performed flawlessly.

Final current output test. Note the system is probably capable of more current output but due to the limitations of the load I was using this was the maximum I could get out of it.

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The next tweak to the computer system was to improve the reliability of the audio cable which supplies an audio signal from the computer to the amplifiers. I originally used a 5M long 3.5mm to RCA jack, but I inadvertently ordered a poor quality cable with even poorer quality plugs fitted to it. Consequently both plug ends of the cable were extremely temperamental and would regularly cause feedback from the computer to play through the speakers or simply not work at all. This problem gradually became worse over time.

To fix this I bought 6M of high quality signal cable from my local electronics store along with two sets of male RCA plugs. I then soldered one pair or RCA plugs to the computer end of the cable (I changed the interface from 3.5mm a stereo plug to RCA plugs as the computer's case has RCA outputs connected to the front panel output header on the motherboard). After that the old cable was removed and the new one ran in its place. It was then cut to length and RCA plugs attached to the other end before plugging them into the amplifier. 

That's it for this post. Stay tuned for future updates and thanks for reading.

I would like to thank my friend for helping me with the audio cable rework and removing and refitting the console for the 3rd time - you know who you are :). 

Cooling Tweaks, UI and FM Improvement

Hello and welcome to post #11 of my blog on building an integrated in-car computer system.

It has been quite a while since my last post; work on the project has slowed due to other commitments taking priority. However significant progress has been made since my last update. I have been tweaking and improving the system to optimize its performance and ease of use. I also performed a full inspection on the internals of the computer to check for dust. More on that later.

The first major improvement to the system was the cooling. As detailed in previous posts, Corsair Link was chosen to run the cooling system. This is a software controlled hardware based system that is versatile for controlling large system's fans and lighting. However, after reviewing its performance I decided that it was surplus to requirements, as there was a better alternative available.  This came in the form of the motherboard's on-board fans controller, which works with the software suite supplied with the the manufacturer. I decided to remove corsair link and instead run the fans directly off the motherboard headers. This change proved beneficial as the ASUS software system does a very good job at controlling the fans and actually runs the computer far quieter than Corsair Link.

However, to achieve this the console needed to be unmounted from the vehicle, the computer removed from the console, and the fans rewired to the motherboard headers.

Computer stripped apart. There is no significant dust build-up in the case or on the components

The wires from the left hand fan needed to be extended to reach the motherboard header but other than that the modification was very straightforward.

Empty rear section of the console where the corsair link controller was

Once the computer was remounted to the vehicle, I uninstalled Corsair Link as it was no longer needed and also interfering with the Asus software. After that, I opened Asus AI suite 3 and selected Fan Xpert 3 (The proprietary fan control software) and activated the auto tune feature. This automatically tunes the fans for specific purposes and gives the user four modes to select how loud they want the fans to run. 

Fan Xpert Softwware tuning the fans

After the automatic tuning was complete the system now manages itself and will automatically adjust the CPU and two case fans to keep the CPU temperature within operating limits. 

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Much more attention has been paid to the quality of signal cable running through the vehicle and avoiding interference. The second major modification made to the system was to improve the FM radio signal quality. Previously I was using the small magnetic base antenna that came with the USB dongle to receive FM radio signals. This was hopelessly inadequate to the point where the radio was unusable. 

As discussed in previous posts, I ordered a complicated system of cables and adapters to adapt the vehicles's factory FM plug to a common plug, extend it up to the roof-space then adapt it again to  the small MCX plug on the dongle. This was a doomed system from the start. Instead of fitting it, I enlisted the help of some friends in the communications industry. They used crimp connectors and a coaxial cable to extend the factory wiring harness, then terminated the extension in a standard BNC fitting.

Terminated BNC fitting with coaxial cable

From the BNC fitting in the photo above, a BNC-MCX adapter cable plugs straight in to the USB dongle. In addition to running a quality coaxial cable to the dongle, the dongle itself was relocated to behind the computer via a USB extension cable. This has also improved signal quality as the coaxial cable ran next to the power cables for the PC and was causing interference.

To complete the system, I also wired the factory electric antenna to a switch mounted overhead in the the switch holder to manually extend and retract the antenna. 

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A major improvement to the windows UI has also been made. The desktop layout of windows was insufficient, so I found software to replace the windows shell with a more touch friendly version. This comes in the form of Thinix Touch. I am still configuring the system as it has many many settings to configure. More on that in later posts.

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Further attention has been paid to cable management and isolation of signal cables from power cables. When rebuilding the computer the power and signal cables for the GPS were separated.

Rebuild console. Note the signal cables for the Wifi/BT and GPS reciever are separated.

The dual band Bluetooth/Wifi antenna has been relocated to the front of the console. However, there have been significant interference/bandwidth problems with bluetooth from the start. If a wifi connection is active on the car computer while bluetooth is streaming audio, it causes the bluetooth to badly stutter and lag. To fix this problem I have decided to buy a USB Bluetooth adapter and run Blutetooth completely separately via a separate antenna. More on that in later posts.

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Finally, problems have arisen in the low quality cable used to run audio from the PC's 3.5mm plug down to the amplifiers. Interference can be heard through the speakers if the cable is not properly positioned. To rectify this I will replace and rerun the cable with high quality leads. And instead of using the 3.5mm plug I will use the RCA ports on the front of the computer case.

I would like to thank my friends for helping me with the coaxial wiring and assisting with the computer rebuild. Your help is much appreciated :)

That's it for now. More modifications and optimizations will follow in coming posts. Thanks for reading. 

Field Testing and Tweaks

Hello and welcome to past #10 of my blog on how I built my own in-car computer based entertainment and vehicle management system. In this post I will discuss  the various tests I put the system through and how it fared.

This past Easter weekend I took my vehicle to a popular camping and 4WDing spot located around a large irrigation water dam. The area includes hilly terrain, bumpy gravel tracks, water crossings, rock climbing, mud flats and muddy holes. I drove my Patrol through each of these multiple times.

My Patrol parked atop a hill climb overlooking the dam.

I'm extremely pleased to report that I experienced no hardware faults of any kind with the computer system at any time during the weekend. This was the first real field test for the hardware and everything functioned exactly as it should from a hardware standpoint. 

However, there were a couple of minor bugs with other parts of the system, specifically the four channel amplifier that drives the satellite speakers. While there were no problems with listening to music at very high volumes (this was tested for an extended period of time), on the second day the music cut out unexpectedly while driving. Closer inspection revealed that the amplifier's inbuilt protection system had activated, possibly due to overheating. The problem soon cleared itself an hour or so later and has not returned. 

There are still many software issues to sort out which i am still working on. 

The next hardware fix I am working on is to improve the FM radio reception through the USB SDR dongle. Currently RF signals are received through the small magnetic antenna which is magnetically attached to the roof, but this is not sufficient for receiving signals far away from suburban areas. To rectify this I have ordered a series of adapters to transmit the signal from the vehicle's factory fitted electric antenna up to the computer and the USB reciever dongle. 

Here is a list of parts that I ordered to do this. 

• Factory FM plug to standard aftermarket plug adapter
• Standard aftermarket plug adapter to BNC fitting
• BNC Extension Cable 
• BCC Female to male MCX to fit the USB SDR stick

In addition to ordering the adapters I have rigged the electric antenna to raise up via a manual carling rocker switch mounted in the roof console.

That's it for this post, as I continue to improve and update the system I will post new updates. Thanks for reading.  

Computer Installation

Hello and welcome back to post #9 of my blog on how I built my own in-car computer system.  It has been a while since I last posted, as I have had other commitments to attend to, however I have made huge progress and have mounted the computer in the car and have it in a working condition. 

Naturally, there was a lot of wiring that needed to be installed in order to get the computer working, so to keep things concise I won't go into detail about every terminal connection I installed. 

In order to save time on installation, I decided to run all of the wiring first before installing the computer. This worked quite well and saved me a lot of time.

Seeing that the head unit was replaced in the previous post by the touchscreen, An amplifier was required to drive the four satellite speakers. I found a second-hand one on Gumtree and bought it for $35, a good deal by any standards.

Second hand amplifier. It is old but still works without any issues.

Unfortunately the amplifier was designed in such a way that it has four RCA inputs; one to drive each speaker and it does not have internal bridging, meaning that four RCA channels are required to drive all four speakers. In addition to this I needed another two RCA outputs to drive my subwoofer amplifier. To solve this problem I made a trip to my local electronics store and bought four RCA single to double adapters and a couple of RCA plugs. I made two short RCA cables from the plugs and an old RCA cable to go from the adapters to the other inputs, and used the double adapters to allow another two inputs for the sub woofer. This is a temporary measure as I will eventually buy better amplifiers with built in pre-amps. 

I extended the wires from the factory head unit harness down under the font passenger's seat to where the amp is housed.

Wiring the power to all of the amplifiers was relatively straightforward. I have created a rough circuit schematic to show how power is delivered to the system as a whole:

Rough circuit schematic. The box on the far left is the passenger's side A-pillar where the wires are ran up to the roof.  The box above and to the right is the compartment above the glovebox where all the excess wires are stowed. The battery in the schematic is the auxiliary battery, the main battery is not shown. Also note that the earth connection for the main amplifier is missing. The two round dots forward of the pc are the two interior lights.

 Running the wires was simple enough, The passenger side A-pillar cover was removed along with the door seal and roof handles revealing plenty of room to run wires along the steel pillar up to the roof.

Passenger A-pillar with some of the wires installed

Compartment above the glovebox with some of the wiring installed. The fuse on the right protects and splits the wires to power the computer and the 4 channel amplifier.

in addition to the power wires, the following other cables were ran;

• 2X 5M USB extension wires, one for the touch screen data and another for the OBD2 interface
• 1X 3M HDMI extension lead for carrying the video signal to the screen. Note I used a HDMI to DVI converter to take a DVI signal from the computer as audio was not needed. I also used a HDMI female to female adapter to go from the male end of the extension cord to the male end of the HDMI plug from the screen's main wiring harness. 
• 1X 5M 3.5mm stero to 2X RCA cable to carry audio from the computer to the amplifiers
• 2X Signal wires for powering on the amplifiers (in schematic above). Note these come separately from the computer as the computer turns the amplifiers on once it has booted.
• 1X 4 core wire for accessory switches on the console
• 1X single core red wire for misc. accessories. This was not used
• 1X mini coaxial wire connected to a magnetic antenna for the FM radio. Until I buy the adapters to adapt the factory radio to the USB receiver stick I am using a small antenna mounted on the roof above the passenger side door. 

 With all the wires ran it was time to make final preparations to marry the computer to the car.

Computer in console with the wireless bluetooth and wifi antenna (left) mounted

Computer and console ready to be mounted.

 With some help, the four screws were installed and the console mounted to the roof once more. This was a slightly difficult two person process as lining the screws up was tricky due to their vertical position.

Console installed. The hole at the from which the wires are hanging will be covered with houses the factory interior light.

Once the rest of the wires were connected the computer was ready for a first test. After a few small tweaks and cable management the computer was fully functional.

Unfortunately during testing an annoying problem occurred with the screen. One of the buttons on its front face caved in, resulting in it becoming unusable and the unit looking broken. In order to fix this I had to remove the screen from its brackets and take it apart in order to fix it. I took this opportunity to do a quick tear-down to see how it worked. After carefully unscrewing it and fixing the caved in button I took a couple of snaps of the main driver board. It turns out that the button had slipped off of the micro-switch that it normally rests against. The cause of this was probably the screen not sitting quite right in its bezel in the dash, resulting in the bezel applying pressure on the scree's bezel and forcing the button off the micro-switch.

Main driver board for the screen

After carefully reassembling the screen with locktite on the screws, I fastened the bracket onto it once more and readjusted its fit in the bezel so there was no pressure on it.  This should stop this from happening again.

The whole install of the computer took me one whole day starting at roughly 8am to finishing at 5pm.

With the computer Installed and functioning, The next stage is to work out the software side of things. I am still doing a lot of testing and configuring on that front. Until I have made a lot of progress and am happy with the way it is running. Bye and as always, thanks for reading.