Thread: feed back issues

Originally Posted by eclipse02

just to start, i have an 02 eclipse gs, im running an intel dg41rq mobo w/ a 500gb hdd and 2g ram. the car has a factory amplifier which is run off of an accessory remote wire for the amp turn on. psu is m2
the problem: on system start up until i get music playing i get a whine almost seeming to come from the alternator, and crackling. also this gets to put waves in my screen (lilliput 629). Ive tried several spots to ground everything and moved the remote wire around to a few places. i'm looking for any suggestions that anyone can have on this issue. my second issue is that when my screen is unplugged, my computer loses power; this is fairly mind boggling to me since the power sources are completely different and the screen is running on the factory 12v outlet plug. any help is appreciated

I may be able to shed some light on the ground noise issue. My setup is installed in a full size conversion van. My vehicle has a full frame and I run everything with an inverter.

As you may know inverters are very noisy. I learned through experience if you keep your ground wire short under 2 feet and it's gauge at a minimum of the gauge of your largest power wire you should have no problems. As an example the ground wire connected to my inverter is 6 gauge.

The ground wire should be connected to a solid member of the vehicle frame. If I recall unibody framed vehicles have very poor grounding sources and it is due to the periodic welds throughout the frame that causes grounding issues.

You might be able to find some pretty solid ground sources in the engine compartment just do not depend on things like the body to act as a good ground.

When I would troubleshoot ground noise I used to take a length of small gauge wire and connect one end to ground and then I would use the other end like a probe. I would have the system running with the head unit on at full volume, no music was needed. I would listen to the ground noise for a moment to get a baseline. Then I would tap the metal HOUSINGS of the various components and other grounding sources connected to or near my installation with the other end of the "probe" wire and listened for a change in the noise. Sometimes the ground noise went away and when it did you were near the culprit of the ground noise interference. Trial and error. I have learned though the major culprit in with ground noise is the "sound out" lead running to your head unit.


CYA/FYI: IF YOU USE THIS METHOD DO NOT TOUCH THE "PROBE" WIRE TO ANY SOURCE OF POSITIVE VOLTAGE.

Not sure about the monitor but I would suspect that even though they are connected to power at different locations it does not rule out the fact that upon shutting off your monitor it could be sending a slight electrical pulse down the video feed lines which could be tripping some internal "short circuit" protection mechanism with your systems mobo and causing a sudden shut down.

Did any of this work ?

so far i tried to reground the system with a larger wire, it has help somewhat and the ground is now on the fuel pump cover screws as it was the shortest place that i could go without drilling new points (the case is temporarily in the back seat until i can find something smaller and more permanent) . tomorrow however i'm going to try to check out more with the remote wire for the factory amp turn on just to see if it'll make any difference. Thank you for the suggestions leo, i'll keep you posted

Sweet, I will tell you though from time to time no matter how well you ground a system it will occur. I noticed too that ambient temperature does matter. It effects the actual composition of the metal and can enable more noise at cooler temperatures and less noise in warmer temperatures. I do not think their is a 100% fix for ground noise all you can do is suppress it. I have poked and proded my system so much now I only hear the heads on the hard drives in the speakers faintly when the head unit is at full volume. Good luck, you can pull your hair out with this one!

so now i put a noise suppressor on the rca lines for the main speakers, moved the remote turn on wire to the factory hu 12v switched line. for the most part the feed back is gone, i still get a winding with the rpms of the car but its much quieter. the only other time i get feedback is right when the computer starts up until the sound card is initialize and sends a signal. hopefully soon i'll be able to almost totally eliminate the sound with some more tweaks

Originally Posted by eclipse02

so now i put a noise suppressor on the rca lines for the main speakers, moved the remote turn on wire to the factory hu 12v switched line. for the most part the feed back is gone, i still get a winding with the rpms of the car but its much quieter. the only other time i get feedback is right when the computer starts up until the sound card is initialize and sends a signal. hopefully soon i'll be able to almost totally eliminate the sound with some more tweaks

The noise suppressor is just a band-aid. If the ground noise is sufficient enough it will eventually overpower the suppressor. I was going to take that route but I had read on here in another thread that it was possible to almost eliminate ground noise with out adding suppressors. The author gave some pretty compelling evidence to support his claim so I took on the challenge. So far I have done as the author claimed could be done.

Now I am not trying to brag but the route you are taking could be costly. The route I took does take more time and more aggravation but it does pay off. As I said before use that "probe wire" and touch the free end to NON ENERGIZED metal components near or on your setup. An example would be your PSU housing, AMP housing, the metal bracket found on the back of the PCI cards included with your setup.

Another trick I have used was to take the ground of the cable that connects to your head unit and split it just before the phono plug at your computer. You would then have the ground wire with a short branch that would be connected directly to a good ground source.

When connecting a ground wire to the vehicle stay away from components with moving parts or wich may contain a motor of sorts. You want to connect the ground to a solid inanimate piece of the frame. Be sure when connecting your ground wire to sand down the connection surface to bare metal and use rigid fasteners as connectors.

It is a possibility I have been so successful because my vehicle has a full "truck" frame and does not use unibody construction methods. I still think though the same principals apply to both types though.

Always willing to assist. Keep me posted...

Ohh yeah, you may know this already but keep all speaker wire and connecting wires between your computer and head unit away from power wires.