General Electrical Questions

**Wiring_Wizard** · 03-22-09, 07:18 AM

If you have an issue, just ask. I may be able to help.

**FlyFord** · 03-24-09, 08:34 AM

Hi Patrick, I gave Marco Flores your number, He is going to call you soon,
His right rear Turn Signal and brake light does not work

Have Fun,
Marlon

**blind** · 03-24-09, 05:36 PM

any ideas on fixing a ground loop condition in a car stereo?

I got a new amp last weekend and it sounds fine with engine off, but I get alternator noise really bad with engine on.

I don't want to use a ground loop isolator because that would filter out ~400hz signals and I'd just lose a ton of midrange...

**Wiring_Wizard** · 03-27-09, 09:10 AM

The only other thing I could recommend is a Cap. Your local Radio installer could help with that.
I don't mess much with the radios but this seems to be a common problem and the radio shop I use told me this works...
Let me know if it cures your problem.

**Glenn_03Cobra** · 03-27-09, 10:09 AM

You can hear at sub 400hz ? 8-)

**Glenn_03Cobra** · 03-27-09, 10:15 AM

Do you know for certain that the alternator is the source?
Is the alt. original? Not suggesting that you put a new alt. on but, I wonder if a new(er) one would do the trick?
Also, are all of your lines in the engine bay insulated appropriately?

**blind** · 03-27-09, 10:28 AM

Originally Posted by Glenn_03Cobra

You can hear at sub 400hz ? 8-)

the amp isn't for my sub, it's a 4 channel 800w pioneer and is driving my front stage JL 6.5" & tweeters (components)
alternator is original to the engine, but not the car, it's not the cause of this.
the sound does not exist with the engine off, and it matches the rpm, it's a ground loop condition and the noise is from the alternator, a ground loop just means there's multiple paths to ground in the audio system and interference is being heard from the current traveling through multiple paths.

it was perfect with my old amp, a kenwood 75x2 150watt amp, which draws a LOT less power and so didn't get affected by this.

I've tried grounding the RCA's and took my ground off the amp and stripped the seat belt bolt and chassis with a wire wheel and no difference.
I also took apart my Pioneer avid f-700bt headunit and replaced the pico fuse on the RCA output ground (which is known to blow out and cause this condition) with a piece of 24awg wire, but no difference from that either.

My positive wire doesn't go across the engine or anything, it's attached to the fuse box under the hood on drivers side, runs through the door channel on drivers side to the amp in the trunk, the RCA runs down the other side of the car.

if it was just a high power sub amp, I wouldn't be able to hear this because the lpf/crossover on a sub is typically set to 125hz.

I have a large capacitor in the garage so I'll give that a shot, I'd like to avoid using that as a bandaide though because it's one more thing to think about when disconnecting the battery to work on the car...

**FlyFord** · 03-27-09, 10:49 AM

I believe he may need to upgrade to a 160 amp or 200 amp alternator, the alternator that he has now its squeeling because it is being over worked and slowing down the pulley causing the belt to slip, YOU can also double check to see if the belt is Tight enough??

**Glenn_03Cobra** · 03-27-09, 11:26 AM

Since he's talking about the stereo and grounding, I assumed he was talking about the alt. static sound that comes through the stereo speakers.

**blind** · 03-27-09, 11:52 AM

yes, there's no noise from the alt, it's a stock cobra alternator which is at least 140amps (it's a 4g)

**92gtconvt** · 03-28-10, 05:01 PM

hey kev, sometimes you get engine noise from running your power cable too close to ( either power or ground ) wires in your car. they say when u get that try running your power cable on the opposite side of the car