Engine whine

**mobileh1** · 05-24-2004, 08:54 PM

Not sure which forum, but this has a bunch of smart people, so I'll try here first.

I have an Epia M10000 in a C134 metal case.
I have a head unit with AUX in.

When the above are connected together there is noise, a whine with pitch proportional to the engine RPM.

If I unplug the computer but leave the bare, unshielded cable free (my first instinct was the cable to the head unit being unscreened) dangling, the whine goes away; so much for the unshielded audio feed theory.

If I plug in headphones into the computer, there is no engine noise.

Its only when the computer is connected to the head unit.

Plugging an MP3 player into the head unit has no noise.

Any ideas?

Thanks!!

**jjh221** · 05-24-2004, 08:58 PM

mine did the same thing with my audio line to the computer from my amp, because i had the power cable for the amp running right next to it. On the forum here is something just like what happend to me. They say to run the power on one side the amp on the other. Where is your computer located and where is the audio line out for it?

**Tidder** · 05-24-2004, 09:01 PM

Best place to start is your ground. Make sure all of your grounds go to the same place. The reason engine noise is heard thru your stereo (so I've read) is because of different lengths of ground travel back to the battery/alternator. Weird Eh? It worked for me though.

**mobileh1** · 05-24-2004, 09:02 PM

The C134 has both front and rear audio out, I have tried both with no difference. The power cables are fed into the rear.

This is the case details:

http://www.***********.com/product_i...roducts_id/183

My power cables are not shielded, I could try that. With the size of the case there is little room for moving things around.

Seems like a number of people here have the same case/setup, I wonder how those have worked out?

**Tidder** · 05-24-2004, 09:04 PM

What are you using for power to the CPU?

**robiewp** · 05-24-2004, 09:04 PM

is your c134 connected to a regulated 12v source? I had this problem when running off the unregulated vehicle's ~13.4v source.

**mobileh1** · 05-24-2004, 09:05 PM

For some reason this forum blanked out the web address of the case detail, so I'll do it again (why?)

http://www.logic supply.com/product_info.php/cPath/23/products_id/183

remove space to see web page.

Why is this happening anyone here an administrator? Have this company been blacklisted or something?

I bought my kit from there and was well pleased with them. Every single post seems to have a car manufacturer mentioned, so why block computer companies names?

**mobileh1** · 05-24-2004, 09:07 PM

regulated yes, ITPS and a 80W PSU, no inverter.

The ground is connected on the computer side to the chassis at the grounding point under the center console, where a number of other things are gronded, scanner, ham radio etc.

The head unit is grounded through its own cable, not sure where to exactly. I could move the computer ground to the head unit ground. I assume the amp is grounded to the same point as the head unit. Not sure though.

**Tidder** · 05-24-2004, 09:09 PM

I agree with Robiewp. You need to regulate your source. Hook all the grounds into the same place. (IE ground of amp, ground of deck, ground of power supply, ground of audio)