i posted something on the audio section, but i'm desparate. i'm getting this whizzing noise when i press the gas because of a power line that runs from the front of the car to the trunk that powers a home dvd unit. it's getting power through a ac/dc converter and power cord. anybody know how i can get rid of this?

here's the link to my message on the audio section:

https://maxima.org/forums/showthread...threadid=11542

 

if its really bad they make a inline alternator noise surpressor...I think schorce makes it....or someone like that....if not buy a DVD player that is made for dc current not home ac current thats likely your main problem

 

I have heard of this before, and it turned out that the problem was a cheap/noisy ac/dc converter, or it could be the typical ground loop. One way to test this would be to power the dvd from an extension cord run to your house. If the noise stops, try grounding both the dvd player and the ac/dc converter to the same spot on the chassis. If the problem is still there, I'd try a different converter. I didn't read your post in the audio section, and there are a number of other things it might be, but try these cheap ones first!

 

Most common reason is the grounding. Check ALL your grounds, battery, Aternator, the DVD, your amps, everything. Make sure they are all clean and making good contact with BARE metal. other than that it may be the ac/dc converter, no remedy for that except replace it with a better one.

 

how do you ground a device like a dvd player? what wiring goes to the chasis?

 

Hmmm . . . interesting dilemna. Here's some thoughts I hope may help lead you in the right direction.

1. As I understand it, you are using a DVD player that was meant to run on standard 120 Volt AC from the home. Well, the power delivered to your home is way more stable and smooth than your car power.

2. Now, the interesting thing is that your are converting 12 volts of DC up to 120 volts of AC. There is and inverse relationship happening in that as your voltage goes up, all else being equal, your amperage goes down. So, if your Cig lighter had a 12 amp fuse, then when you upped the voltage to 120 AC, your available amperage went down to 1.2 amps . . .and that includes the converter AND the DVD player.

3. Another interesting thing is that all audio components for the home convert the 120V AC down to usable DC, like 5 volts or so. So your car system is converting DC to AC and then finally back to DC again.

To fix this I would;

1. Install a capacitor in-line with the cig lighter outlet, thereby smoothing the voltage being delivered to the ac converter.

2. If possible, use a connection to the fuse block with higher amperage. There must be a 15A connection you can use, if the cig lighter isn't already a 15 A socket.

3. If possible, bypass the AC converter completely and step down the DC voltage directly into the DVD (Bypassing it's AC input and connecting to the unit internally) Find its internal DC voltage and use the appropriate resistor to step down the 12 or 13.8 Volts DC to the 5 or 6 it needs.

OK. The 3rd suggestion is a bit of a stretch . . . .

Hope this helps!

DW