HELP NEEDED! Eee PC and headunit = wierd noise

**WraithJ** · 01-12-2009, 05:13 PM

Hi, ive been posting on the forums on and off for a while and have started to build my own system. Im stuck atm though due to a problem.

Before i describe the problem, ill describe the setup.
1. EEE Pc 701
2. Alpine ipod headunit with 3.5mm jack adapter cable
3. 4 way cigarette adapter
4. halfords multi power adapter

I have tried this with two different cars, and two different adapters, also without the 4 way adapter.

Basically when i accelerate i get a whining noise, similar to a power steering pump sqeauk noise. Now i know ground loop isolators are for fixing noise like this but, im not sure in my case as I have no amp or sub yet. If i unplug the power it sounds great! The other thing is the power adapters have to be set at 12v, not the 9.5 required by the eee pc, as 9 is too low and neither adapters have 10! I work as a PC technician and i know over feeding a voltage is not the best idea, but ive tested it charging on a 12v adapter all day and doesnt seem to be doing any damage!

Do I need a specific 9.5v adapter to sort the noise out, or a ground loop isolator?

Any help would be amazing!

**GizmoQ** · 01-28-2009, 06:45 PM

Saw your "threadjacking" post and thought I'd chime in. First thing you need to do is STAY AWAY FROM CIGARETTE LIGHTER ADAPTERS!!! You'll need to find an ACC power source preferably from your fusebox with at least 25A fuse.

With that said, go out and buy an Asus EEEPC auto adapter. Here are a few I googled:
Asus Accessories
Mobile Advance
Provantage
EBAY

I recommend the OEM one from Asus cause it has the brick (transformer) and a long cord. Take the end with the cigarette lighter adapter and cut the adapter off. Wire the positive side to the fuse box and find a really good ground point, i.e., bare metal (frame rail is best) and attach ground.

If you still have noise, you'll have to attach the positive side of the car adapter to the battery through a Startup/Shutdown Controller.

Good luck and throw those cigarette lighter adapters away.

**BlackStealth** · 01-29-2009, 07:19 AM

Originally Posted by WraithJ

Basically when i accelerate i get a whining noise, similar to a power steering pump sqeauk noise. Now i know ground loop isolators are for fixing noise like this but, im not sure in my case as I have no amp or sub yet.

You don't need an amp or sub to have a ground loop problem.

**WraithJ** · 01-29-2009, 12:26 PM

OK, so atm i have two cigarette adapters with adjustable voltages, i have used both set at correct charge and still no good. Tried without battery and tried with thoose anti interferance ring magnets and still no joy! GizmQ, can i use either of the ones I have atm or do i need to go buy a new one? Would one of thoose cigarette to standard wall socket converters work or not?

**rdholtz** · 01-29-2009, 12:44 PM

Originally Posted by WraithJ

OK, so atm i have two cigarette adapters with adjustable voltages, i have used both set at correct charge and still no good. Tried without battery and tried with thoose anti interferance ring magnets and still no joy! GizmQ, can i use either of the ones I have atm or do i need to go buy a new one? Would one of thoose cigarette to standard wall socket converters work or not?

I'd bet that GizmoQ is right on with his comment where he says "STAY AWAY FROM CIGARETTE LIGHTER ADAPTERS!!!"

Wire directly to the system as he recommends. The point is not whether there are "good" or "poor" cigarette adapters; the point is that they all suck; it's only a matter of how much they suck. If you want high quality results, you need to take a professional approach, and the pros don't use cigarette adapters.

All that being said, you may not completely resolve this problem with that single change. There may be other glitches as well. But this is a great start, and should help.

Like all troubleshooting, you start with known weak points, or the most likely weak points, and fix them. Then keep on fixing things until the problem disappears or is improved to an acceptable level.

**GizmoQ** · 01-29-2009, 01:36 PM

Originally Posted by WraithJ

OK, so atm i have two cigarette adapters with adjustable voltages, i have used both set at correct charge and still no good.
Tried without battery and tried with thoose anti interferance ring magnets and still no joy!

As expected.

Originally Posted by WraithJ

GizmQ, can i use either of the ones I have atm or do i need to go buy a new one?

I think you're beating a dead horse here. First, using a cigarette lighter is dangerous and second its one of the poorest sources of power in the car for numerous reasons. Don't just take my word on it (evidently you don't), search the forums for "cigarette lighter adapter" and read, here's some to get you started:
http://www.mp3car.com/vbulletin/866955-post12.html
Inverter mistake?
http://www.mp3car.com/vbulletin/car-...my-laptop.html
Question about powering PS2.
http://www.mp3car.com/vbulletin/835432-post7.html

Originally Posted by WraithJ

Would one of those cigarette to standard wall socket converters work or not?

If you're talking about one of those that plugs into a cigarette lighter, NO, with that you now double the noise.

**WraithJ** · 01-29-2009, 02:02 PM

Ok, i take youre word for it and i will look into changing it, however upon taking some advise in rdholtz thread, i tried with some good external speakers, and guess what no noise. So this means it isnt the charger that is cuasing the interferance, im betting its the alpine specific cable, ive had a bad feeling about it from the start as it feels a little loose in the plastic surround (jack end)!

So youre suggestion gizmoQ, is that I buy a OEM car adapter, cut the cable near the cigarette adapter, then connect the positive, to a fuse, the negative straight to the battery terminal then ground it? Will the adapter have all three wires in the cable, or will i need to solder on a ground wire? Can I use a fuse like the ones you get in amp wiring kits, or does it need to somehow connect to the fusebox. I have some experience with home electronics, loads with pc's but and some with car audio, but ive never really delved into any serious car electronics before, so i do need a bit of guidance.

**WraithJ** · 01-29-2009, 03:20 PM

Ok another quick update, just been fiddling around in the car. I tried foil wraaping the input cable (as suggested by rdholtz) and no luck, also fitted the isolating magnets more evenly, now one on the charger, one on the input cable jack end, one on the input cable head unitend, and one on each of the two iso connectors! Again no joy, but fortunately it looks like the whole din socket and the cash pocket below, will with a little bit of sanding be exactly the right size to hold the 7" lilliput TS im stillll waiting for!

**midnightracer** · 01-29-2009, 03:21 PM

there is alot of great information in the treads posted before.. and just because you used extenal speakers does not mean you have beaten the ground loop issue. Dc current flows to ground... so the shorter your ground wire the better.. it also depends on how good of a ground you have for both your source unit(pc) and your receiving unit.(Alpine head unit). You seem to know enough to tackle this task.. so why not try to shorten your ground.. as short as possible without interfering with your install. on the pc.. and yes any general inline fuse will work on the positive side..just no longer than 6 inches from the source of your power. that will save you from a ground short that could happen and setting fire from the power source all the way back to where your fuse is.. i would get aconstant 12v from the battery and if you need switching get a standard 12v 30A bosch relay. As for your head unit.. it typically will have a long ground on it.. unless you drive a vehicle that has isomounting of the headunit or a chrysler Try removing the ground from the headunit and giving it a chassis ground also as short as possible.. that way you eliminate possibility of a long ground in the factory harness. and last but not least. the cable going to the headunit.. its most likely not sheilded... so it has fo be roughted to your vehicle headunit away from power sources... these sources dont just come from your pc or the wire you ran for 12V .. but it may be from sources you cant see..from electronics in the dashboard.. so move it around some and play with it before final mounting.. you might find your problem anywhere in the above listed . if it is the aux cable... you may be able to extend it and run a differeent route if cable is not long enough
sorry so long..

**Tidder** · 01-29-2009, 03:50 PM

Try connecting the ground on your audio cable (or the audio jack if your eee is taken apart) to the ground of your cigarette lighter outlet. It fixed noise/engine whine I was having when I was using an inverter. (except I hooked it to the inverter's input ground since I wasn't using the cigarette lighter outlet)