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Install Power Supply for Mac Mini Computer


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I've bought a Carnetix P2140 power supply that provides intelligent regulated power to any in-car computer that you might have. In my case I am installing a Mac Mini in my 2001 Boxster.

Basically you connect the PSU to the battery, but there are additional wires to provide a pulse start input (typically from the car alarm system allowing you to start the computer before you start the car when you open the doors with the wireless keyfob). Also there is an input labelled Ignition that I think starts the PSU based on the ignition key being turned on.

I understand it conceptually but am at a loss to knowing where I can actually physically tap into these wires from in the existing car system.

Can someone point me in the right direction to where I can tap into -

1. Ground

2. 12V+ (note that I need the full battery power and that e.g. the spare cellphone connector would not be powerful enough)

3. The pulse voltage signal that occurs when the keyfob is activated.

4. The ignition switch on signal.

I am guessing that the PSU itself would be best mounted in the centre dash somewhere or perhaps it could go in the front trunk?

I am totally unfamiliar with where the physical location of these wires are so as much help as possible would be appreciated.

Here's the URL of the PSU in case anyone is interested in finding out more about this product.

http://www.carnetix.com/installation/P2140...Manual_V1_2.pdf

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I'm not sure where you can get the 'pulsed' line from, but the ignition on can be run off the phone power hook up behind the center consol. It's a plug that looks somewhat like a 4pin trailer wiring harness. Here's a color code/description I did after I hooked up my sat radio using it.

43geirs.jpg

As for the full power line, why not just run a dedicated line to the battery? Do a search on the rear speaker kit or 6x40 amp swap and you'll see there is a plug (about 6" above the gas pedal) that leads right behind the battery.

Good luck and post some pics after you install.

** note to self - edit the picture size someday

Edited by Cassiebox
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Nice diagram. Thanks that is a great start. So the green and black one will give me my ignition on pulse - is that correct?

Its a nice idea to run straight from the battery but it might look a little messy - I'd prefer to tap off of something that is already on the cab side of the firewall. Maybe somewhere near the fuse box. There doesn't seem to be any documentation anywhere...

(Actually, hold on, I've just looked again isn't that ignition switched 12V+ only for the phone and consquently only about 500mA?)

Edited by joesan
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Nice diagram. Thanks that is a great start. So the green and black one will give me my ignition on pulse - is that correct?

Its a nice idea to run straight from the battery but it might look a little messy - I'd prefer to tap off of something that is already on the cab side of the firewall. Maybe somewhere near the fuse box. There doesn't seem to be any documentation anywhere...

(Actually, hold on, I've just looked again isn't that ignition switched 12V+ only for the phone and consquently only about 500mA?)

Can't tell you for sure, but for some reason I thought it was on a 7A fuse. If it's just a trigger (for a relay within) as you suggested, it won't need whole lot of power. Anyhow, I guess just crack out your fuse panel diagram or Bentley manual and find some places to tap off of the block. Also, if run a search in the archives on carputer and you'll get some hits as others have done what you're trying to.

Good luck.

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I'm using the same power supply on my 996 MacMini install project. I'm going to put it under the front hood where the original CD Changer was. I'm going to grab switched power from the original stereo harness. I'm going to grab power straight off the battery as it's a pretty beefy supply. I'm not using a pulsed input.

Where do you plan on putting your Mac Mini? I wanted to use the glovebox but the wiring harness proved too be too bulky. It's going under the hood too.

My project has been stalled for a few weeks due to work & travel, but I'll be picking it up again soon.

Here's my worklog:

http://www.mp3car.com/vbulletin/showthread.php?t=92248

Edited by DiscobayJoe
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Cassiebox - thanks again for the input. Good suggestions.

DiscobayJoe - Actually I previously read and really enjoyed your worklog but then it seemed to stop for a while. My next step was going to be to ping some of the guys on the MP3 car forums to see how they'd done theirs.

The Carnetix supply looks great. One of the reasons I got it was that I want to be able to run an extra hard drive for my entire CD collection as well as the screen, GPS etc.

I guess I could take power straight off of the battery - just thought that that might look a little messy so would have preferred to tap off an existing wire somewhere.

I'm not sure if I understand the concept of the switched ignition power - I'm hoping it is just a pulse (to tell the PSU to switch on)?

As regards placement I also thought about putting it in the front trunk as it would be pretty neat in there. There is no Glovebox on my Boxster so that is out. My other options are a] in one of the Din slots in the console b] Under the passenger seat or c] there is a space behind the passenger seat where I believe that the CD changers go in the boxster.

I'm just nervous as hell about blowing my electrics so I'd love to see how others have done their installs. If I do figure it out I am going to photo it to help others. All the other parts of the process seem to be well documented on the web.

Edited by joesan
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I'm not sure where you can get the 'pulsed' line from, but the ignition on can be run off the phone power hook up behind the center consol. It's a plug that looks somewhat like a 4pin trailer wiring harness. Here's a color code/description I did after I hooked up my sat radio using it.

43geirs.jpg

As for the full power line, why not just run a dedicated line to the battery? Do a search on the rear speaker kit or 6x40 amp swap and you'll see there is a plug (about 6" above the gas pedal) that leads right behind the battery.

Good luck and post some pics after you install.

** note to self - edit the picture size someday

Do you know, Is there a connector like this in a 987?

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Westcoaster-

I don't think there is one in the 987. However, you could either run a line over to the fuse panel, or tap off of the existing cig lighter lines - depending on what you want to power. I have a 986 so I'm not sure if the 987's cig lighter is keyed w/ the ignition or not. Sorry can't help you much other than that.

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Westcoaster-

I don't think there is one in the 987. However, you could either run a line over to the fuse panel, or tap off of the existing cig lighter lines - depending on what you want to power. I have a 986 so I'm not sure if the 987's cig lighter is keyed w/ the ignition or not. Sorry can't help you much other than that.

I am trying to find a switched line to trigger a relay for lights, seemed like a easy task but so far no luck. I think that I have like 4 or 5 threads open on my failing HID headlight project. :cursing:

The cig outlets are all on all the time... I just figured if there was something like the phone power it would be an easy find.

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I got a clue about how to solve your problem by looking at this product:

http://www.pcars.com/shop.php/porsche/boxs...-coupe/p_5.html

which taps into the key remote signal. From the looks of their connector, it seems as if it intercepts the signal at the ECU. The ECU is easily accessible by pulling back the carpet in the rear trunk.

I've seen the ECU pin diagram here somewhere but I'm having trouble finding it right now. The gurus (ToolPants, Loren) probably have it.

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hi joesan,

i'm not sure if i understand this completely, but here are my thoughts.

use the 4 prong power outlet under the center console. if the wires are not long enough, cut the 4-prong plug off of the wires, terminate them with bullet connectors, and you can add extensions to the factory wires so that you can place the PSU wherever you want. i would think that the front trunk would be the best place for it. is it very easy to run the wires from the center console into the front trunk area.

the 4-prong power outlet has everything you need. constant +12V, switched +12V and ground. you mentioned that you weren't sure what switched power is. switched power supplies no power unless the key is turned, as opposed to constant power which is always on, regardless of key position (like the cigarette outlet). i really think that using the 4 prong outlet will be the easiest way to do it.

i'd also locate the computer in the front trunk. that's where mine is...

2240.jpg

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I don't think he has everything he wants from the phone plug. He wants a signal that tells him when the alarm is deactivated, presumably to boot up the computer from the remote so that it is ready by the time he turns on the car and turn it off (initiate shutdown) when the alarm is activated.

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I don't think he has everything he wants from the phone plug. He wants a signal that tells him when the alarm is deactivated, presumably to boot up the computer from the remote so that it is ready by the time he turns on the car and turn it off (initiate shutdown) when the alarm is activated.

ahh, that was the part i wasn't getting. got it now. ;)

although he could use the 4-prong plug for everything except that pulse connection, and just run a wire from the DME to the PSU, right?

Edited by Chris_in_NH
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It depends on how much power his PSU requires. IIRC, the telephone plug is relatively low power and probably won't be sufficient for a Mac Mini, which is not a mobile (read: low power) computer.

I would personally wire a new circuit from the fuse box. There is at least one blank slot in the fuse box for just that purpose. It makes access to the fuse very easy. He may even be able to connect the computer to the stock amplifier bracket, which could keep it out of the way of everything and could make for a very clean install.

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Richard's right I have a UK model 2001 Boxster so I doubt that the phone connector is there. Also the PSU is substantial and I don't think that the phone supply is beefy enough.

I am beginning to think that it might good to install the PSU and the Mini in the front trunk. I have the amplifier upgrade so I cannot use that spot but was thinking that the Mini could go in the space where the CD Changer would go?

With Richard and Stefan's guidance I was considering the following connections -

1. +12V - Direct (fused) connection to the Battery

2. Ground - Direct connection to the Battery

To be honest I'd rather have connected the PSU somewhere other than directly to the battery as I think it doesn't look very factory to have additional wires coming from the battery but am not sure where you would do this (fuse box?).

3. Switched +12V - From the Ignition (Richard tells me I can get this from the Relays in the drivers footwell - I'll need to investigate exactly where)

4. Pulsed +12V - From the door unlock pulse A19 (as per Richard/Stefan)

Does this seem right to people?

I like the idea of using the existing fuse slot but am not sure how to go about it. Anyone have a photo of how one would make the connections?

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I still recommend using the stock fuse box, even if you are planning to put the computer in the front trunk. It will require you to run one wire (power) from the fuse box to the front trunk. That isn't very difficult. There are some holes with other wires already and you can put it through there.

There is a spare fuse position for this purpose. I don't remember where it is off the top of my head but the fuse list shows it as something like "Spare Accessory (unused)". I used it to add a second cigarette lighter in my car.

I can provide better instructions regarding the fuse box later (when I'm at home). But basically, you unscrew the fuse box (4 philips screws), pull the fuse box out, add a metal pin in the back (to hold the fuse - you'll have to get this part), and connect the wire from the common power cable (which goes to all of the fuses) to that pin. Once you pull out the fuse panel, it should be more obvious.

Ground you can get by connecting to any of the many existing ground points on the chassis. There should be some in the front trunk. In fact, I'd bet that the ground on the battery goes directly to the chassis.

----

What are you going to use switched power for? Are you going to introduce a delayed shut down after the accessories are turned off? You'll need a timer circuit and extra relay for that.

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Stefan - sounds good. I would be keen to use the fuse box solution as it sounds like it would give me a neat installation.

I believe that the PSU can handle the full output of the battery so there shouldn't be a problem there. It is important that I give the PSU full Ampage (e.g. the phone connector would only have provided about 500mA).

You're correct I am using the switched power to initiate and stop the computer in a controlled manner. The PSU I am using, the Carnetix P2140, has all the circuitry to handle that automatically built into it already. I just need to source the pulse signal and the ignition signal.

Any other pointers you can give me on the connections is much appreciated.

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I just looked up the Carnetix P2140. That's a pretty cool device. I didn't know they made such a thing.

I will post more info soon. I was too busy last night to do it.

As Chris pointed out, you can get switched (by the igntion) power from the telephone cable. But I suspect that that is not what your PSU is looking for. They are probably looking for a non-powered signal (connectivity or connection to ground). You can get that using a relay from the telephone cable if you have to. But there is probably an easier way. If I send you the wiring diagram, are you capable of figuring it out? (I don't know how good you are with this stuff) If not, I can take a look at it but I am pretty busy so I might not get to it right away.

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Stefan - a wiring diagram would always help but explicit expert guidance is even more beneficial. I would say that I know enough to be dangerous but I am trying to learn!

I think that the PSU has its own relay bulit in so if you send a pulse it can utilise the +12V power.

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