power inverter interference

[Fish Man]

hey everyone. I have a power inverter wired up in my car for my laptop. i also have the auxillary cable hooked up to my pioneer head unit so i can play music and movies on the computer plus use it for my ipod. i had a small inverter in at first (150/300w) and i figured that would be plenty for my computer but since i use it often when the car is off, i was wrong. i picked up a 400/800w. inverter and have that in now. it powers the computer just fine and im happy with that. however, when i have the computer plugged in to the inverter and the head unit at the same time, i get awful feed back. if i have the computer hooked up to the head unit with the power inverter off, there is no feed back. however the second i turn on the inverter it gives feedback. if i plug the computer in to the wall there is no feed back on the stereo. i can run my computer off of the inverter and have an ipod hooked up to the stereo with no problems. ive tried all these crazy combinations to try and make some logic out of it but i cannot. i took the aux wire and pulled it out to get it away from any possible interference sources and no luck. i put the inverter under the hood and hooked it up to the battery thinking that maybe the aux cable was too close to the inverter but that gave me interference too. i could really use some help here. hopefully it is something simple and somebody will chime in and make me feel stupid thanks in advance guys, you always seem to answer my rediculous questions.

 

[Doug]

Try using a ground loop isolator, it plugs inline with the audio connectors and you can get them at radio shack for about 15 bucks. you can also try grounding your laptop to the truck with a piece of wire, they may reduce/eliminate the interference.

 

[FexplorerV8]

get a sound filter, it should get rid of the noice, to install it you would connect the rca's coming from the laptop to the filter and the other end onto the HU, i think i have some pics on my cardomain, take a look, also grounding the pc MIGHT help but i doubt it...
you need to remember that the HU its grounding the laptop trough the RCA's Cables trust me it does even though it sounds crazy so just get the sound filter and tell us what happended.

 

[Fish Man]

ground loop isolator, sound filter...anything else?

 

[boominXplorer]

get all the audio and power wres as far away as you can from each other

 

[TeamPwnageBrad]

a ground loop isolator is just a patch for a faulty wiring job...

 

[Fish Man]

sooo whats the bottom line? what do i really need to do? i dont think that the wire is too close to any power wires or anythign cause it runs fine with the ipod. i even pulled that wire out and it didnt help any. i dont believe that i have a faulty wiring job so the ground loop isolator would be irrelevant? i dunno what the problem is. i can have the power inverter powering something, as long as it isnt the computer i dont get feedback.

 

[Doug]

I highly doubt you're getting ignition interference. I'm willing to get the reason you're getting as much feedback as you are is because you're using a cheap inverter. Most inverters you buy unless you spend big $$$ are non-sinewave inverters which means they put out a pretty rough AC signal. Alot of times this poor electrical source can cause feedback, try grounding your laptop first, use a piece of wire with an alligator clip on each end, I'm willing to bet you'll notice a difference. But don't listen to me I only fix electronics for a living.

 

[Fish Man]

yea, it is a cheap inverter, which i have heard about the whole non sine wave signal...which kind of wave do they put out, i forget. sooo grounding the laptop...where would i hook it to on the computer? i assume stick one clip to a ground on the car but where should i ground the computer? thanks

 

[Creager]

i think your real problem is converting DC to AC then your laptop converting AC to DC again...

DC to DC converter?

im not an expert like doug, but i had a simular issue trying to put a computer in a car, fixed the issue with a DC/DC converter.

 

[Doug]

You can get a DC - DC converter but a decent one for a laptop is around a 100 bucks, I agree this would probably be an idea solution. You can clip the wire to anything metal on the laptop and anything metal on the truck.

 

[Fish Man]

hmm...sounds like i ought to try grounding it then. thanks guys, ill let you know what happens