Thread: CarPC, audio\interference issue.

Originally Posted by iNcArCeRaTiOn

I've got my carpc up and running now, and now it's time to work out the bugs. =]

so, the first thing i notice when i turn it on for the first time is there's an annoying interferance noise coming from my sound system (i have it hooked up to my head-unit directly from the audio out of the carpc). it's a humming noise, and according to the RPMs i will get either none or a lot of kind of louder (than the humming) constant high pitch squeeling noise. i can also hear my engine louder, it's like there's a microphone in the engine compartment next to a certain part or something.

it's not the connection to the car either cause i hooked up my Pro-97 Scanner and it sounded crystal clear, it's like something's not grounding properly or something.

thats probably exactly what it is... a ground loop. make sure the spot you ground the psu to is clean and bare metal. also try to limit the amount grounding points you have. all amps, pc's and anything else should be ground at the same point.

Originally Posted by iNcArCeRaTiOn

then my other problem with interferance is my LCD touch screen is having like waves like a tube television would have when there's a HUGE speaker next to it or something. it's not the screen cause i've had it hooked up to another computer and worked great.


any ideas\suggestions\comments appreciated =]

i love it though, it'll be great once i get rid of the kinks, i'm using RR with digitalFX skin

the rippling is a power issue. you may want to tap of your psu if you have the juice on the 12 volt line or you could also buy a point of load psu as a dedicated clean 12volt power source. but first check out the ground. are you running it off of the cig lighter socket?

you know, i always wondered if adding a cap in line with the screen power leads would help solve the scrolling.

the psu has a neg, pos, and acc lead that you wire into. check the ground on that lead

If it's picking up the nosie on the video cable, you might want to install a ferrite close to the screen on the vga cable. Otherwise, a clean power supply should help. What screen are you using? Liliputs usually come with an egg shaped regulator on the power lines.

You might want to look around or search in the LCD section, I think people have discussed ways of fixing it before. I wonder too if a small cap connected across the power lines to the screen would help smooth it out or not. Dunno?

i had the PSU wired up by some friend at bestbuy in the mobile install bay, so i'm not sure what he connected those too, i'll have to ask him about that but the audio is really bugging me.

i checked the PSU it's screwed onto the little pegs and not touching anything else neither is the motherboard i put something under it so it doesn't touch the case below it.

it has to be something with the mini-itx PSU though cause if i hook it up inside the house with a normal ATX PSU and hook the speakers up it sounds crystal clear. what else would it be? should i get rubber washers between the PCB board of PSU and the pegs or something?

should i have the guy change the wires to what they're connected to as far as the power feeds?

i've tried a different audio cable too just seeing if it was something simple, same thing.

thanks

did you check the grounds yet? i'm not talking about how the psu is mounted but how it is grounded

nope, like i said i'm not sure where or what he grounded it too, i'm gonna ask within a few days when i see him at work. then i'll get back with you\you guys here.. =]

ok, i'd put money on it that it's a grounding issue

Just to chime in, If you want to eliminate the waves on the screen, another option you can do is to get +12V from the power supply. Given that your PSU can handle the extra current. I believe that the cig lighter wires is more prone to noise. And it is possible for the noise from the screen can be picked up through the motherboard to your audio output. Another reason why I like optical. I wont bore you with that though.