My 2002 TJ Exec has a standard single CD radio.

The problem is that whenever I turn the headlights on the radio emits a soft buzzing sound from the speakers. But when I use the radio during the day (ie, no headlights) there is no problem at all. It's very annoying.

Does anybody know whether this a common problem? Or can suggest a diagnosis? THANKS!

Common problem in all car audio. Its called ground loop interference.
The reason for this is due to the negative ground in ur car. Cars use this to save money in wiring, by grounding the battery negative to the chassis. So the entire chassis becomes the cars ground.

So essentially, the headunit is using the same ground as ur headlights. When the headlights turn on the current through the chassis changes affecting the headunit.

Now if the headunit has a poor ground, whilst most of the current that powers the headunit will go through that ground, some of it may also try and go through the RCA leads or speaker wires. When this happens the stereo's audio output circuitry becomes part of your car's electrical system. So every part of your car can potentially affect the output by the speakers.

Check ur headunit ground or amp grounds, ensure they are securely mounted to bare metal.

Peace

Tim

I sort of have the same problem. My radio has heaps of interference when i accelerate. Does this mean my engine is interfering somehow?? same sort of thing or completely different??

That could be antenna, or engine noise.

3 main sources of interference,

Induced noise - Caused from current running through a cable which creates electro magnetic field around the wire. Any low level wire running past this or adjacent to it will pick up this interference. eg RCA cables running alongside power cables

Thermal noise - Which is the problem associated with heat and electrical equipment, as we cant operate our equipment at 0 degrees all the devices in ur car will create some thermal noise. Damaging the signal to noise ratio. Best bet is to use a headunit with high voltage outputs. (at least 4 volts)

Ground loop - covered b4.

Finding these problems can take ages, anything in ur car can be a potential source of interference. The main ones are rca's running next to power cables and poor grounds on the headunit or amps.

Peace

Tim

Hi Stewart
Some great info there from s_tim_ulate. If you only have a standard system ( no amps, etc) then I have given a solution to your other post in general forum :cool:

do u get that problem when your key is on the 'on' position? (or whatever the click just before the engine starts)


i think its time for u to get a new headunit stewie!

could this possibly affect a sub's output????

if there is a bad ground somewhere in the car???

Absolutely, especially if you have a lot of power.

Main one to check is that ur amp ground is thick. short and mounted to a solid area that is sanded back, with good contact. (eg baby restraint)

Peace

Tim

nodz because i went through my entire car...

- attached subs to someone elses amp - sub worked fine
- attached amp to someone elses subs -amp worked fine
- ran my rca's to someone elses amp - not the deck terminals

then by doing all the tests below i came with the same result

- swapped my ground to multiple places eventually had it earthed to the spare tyre bolt...
- checked my remote, in the end just had it getting constant power for testing.
- checked my power line to make sure it wasnt damaged in anyway.
- made sure that my rca's werent being interfered with
- made sure sub wire was a decent size

i had every wire out of the car running individually to try and isolate the problem and still having subs playing pulsating bass but not the bass from the input... even when my sub control on the deck is turned off it plays pulsating bass. like there is interference somewhere...

the only thing i didnt try was another battery.. is it possible that there is a lot of ground interference in the car already.. hence would putting a battery in the boot and running + to + and power to - do the job?

also if i did do this would it be worth getting a capacitor? how long could i expect the battery to last?

thanks for your help!! :D

p.s. sorry for thread hijack :)

jpeg run another set of RCA's i know you said u try it to another amp but replacae it and see what happens

jpeg run another set of RCA's i know you said u try it to another amp but replacae it and see what happens

rca's are brand new i've tried 3 sets of brand new rca's and got the same outcome :(

rca's are brand new i've tried 3 sets of brand new rca's and got the same outcome :(


They arent running anywhere near your power wires are they, that sometimes causes interference iirc

i had every wire out of the car running individually to try and isolate the problem

i bought 5 metres of ground cable today and im gonna run it straight to the battery to see if that has an impact

i bought 5 metres of ground cable today and im gonna run it straight to the battery to see if that has an impact


Try running a new earth from battery to chassis, then a really short earth from amp or HU to the chassis. Make sure you sand the earth point back to bare metal, also check the terminals you are using that there is no problems with them IE that they are of good quality with decent plating on them. Long earths arent always a good thing im sure tim can explain why better then me.

as always if im wrong, please correct me

cheers

brad

nodz but i guess the way i saw it was, earthing it to the battery is better than earthing it to the chassis. no matter where you earth it its going to run back to the battery (which is the whole point)... because if your earthing it to the chassis then it has to run through the chassis to the ground wire connected to the battery...

so theoretically if i ground it straight to the battery i shouldnt havea problem with interference from the chassis (if thats the problem) :)

hmm, exciting problem you have here

pulsating? whats the problem again? noise? no bass?

your alternator still healthy?

Most of hte time the grounding should be fine. I added an extra ground cable to the chassis, 4ga cable, sanded back a hole i found on the engine mount next to the battery, and bolted it in there. NO difference, but theoretically, there's supposed to be :confused:

and yeh, TF630, you are correct.

what stuff r u running jpeg? if ur cabling is all fine (incuding fuses, some dodgy fuse holders/fuses can cause a lot of resistance too) then it could be your amp...

did it sound all perfect in someone else's car?

earth to the chassis because you get more resist. though a thin wire then the body of a car

yeah we ran all the equipment in someone elses car and worked fine.. we even ran the amp and subs in someone elses car using their wiring and used my rca's worked fine...

the subs just pulsate constant bass... even if the CD's on pause or the sub control on the deck is turned off..

could another problem be fluctuating power???

as for the alternator.. when i've been testing car hasnt been turned on... would alternator still have an effect?

No the alternator won't have any effect if the car is off, and in fact, because almost nothing is running, you shouldn't have interference issues.

What head unit and amps are you using? Some head units with CCFL and other similar backlighting can cause induce interference.

What happens when you unplug the RCA's from the deck (with the amp and deck running)? Then what happens if you have teh RCA's plugged into the deck but have the deck powered off (Try unplugging the power lead or fuse not just by pressing the On/Off button on the face)?

i've had the amp running without the rca's plugged in and there is no signal coming through the subs...

all components have to be connected up to the amp for the subs to create any sound... so
- power earth and remote must be connected.
- rca's must be connected
- sub wire (obvoiusly :P) must be connected

which is typical...

i havent tried

linking my amp, subs and wiring (to my car) upto someone elses deck via rca's

will test that tonight if i have no luck with anything else... it could possibly be the deck ground... which coincidently i do have earthed to the same place as the ccfl's i have in the front... however the ccfl's were hooked up while the sub was running fine before...

Sorry I forgot most of you guys are running the remote lead directly from the head unit. Could you try to re-wire it to constant power and then try switching the deck on and off?

nodz i had constant power to it.. but i didnt try switching the deck off to see the result.. something else to try :) ty

ell after a lot of screwing around tonight had no results..

issue still stands..

tried

-alternate battery. (no effect)
-multiple clean grounds
-ground cable to battery with platinum ring
- 2 more sets of rca's
- tried all 3 preouts from deck
- tried all three channels on amp
- unplugged ccfl's and any other devices that may have caused interference


im running 8 gauge power for a "1200" watt max amp... note its boss so probably only a quater of that rms... but dont know if this would be the issue because it has been run with an 8 gauge power wire in a falcon...

only thing i didnt substitute was the fuse and fuse holder...

thanks for you all for your help and suggestions!! i really appreciate it!

i shall see if my sleep envoke any inspiring idea's :rant:

im off to bed..

What are ur gains set at?

When u pump ur stereo, what percentage of the max volume do you reach.

If you dont get near 3/4 then turn the gains down on ur amp. This will result in a stronger signal getting through, and ur amplifiers wont have to amplify the distortion as much.

May have been asked b4, but i cbf reading... What is the size of the ground? HOw long is it? Where is it mounted?

So, hmm, did you try having the amp powered up with RCA's connected to the deck with the deck off? If so, what was the result?

What about when you unplugged the RCA's from the deck but leave the RCA's connected to the amp. (In turn, dodgy RCA cabling will produce ill effects due to the cabling acting like an antenna).

Just read through the whole thread, JPEG, ur issue doesnt sound like intereference. Grab a walkman or portable music player and plug it into ur amp. Press play and tell us what happens? Is the problem still there?

Ur amp may be screwed. Or ur rca's may be shorting out somewhere/headunit giving u grief.

More elaboration on the actual problem? Does it occur when the car is moving? Does it go to the revs on the car, does it occur when the car is bumped. will it happen when the car is still? Ignition on/off etc etc... What does it sound like again? :confused:

Probably something simple... Have you checked the phase of ur subs? (if you have two)
if they play constant bass ur rca's may be shorting against 12v or the ground. Check to see the rca heads arent touching anything behind the headunit or at the amp.

Peace

Tim

So, hmm, did you try having the amp powered up with RCA's connected to the deck with the deck off? If so, what was the result?

What about when you unplugged the RCA's from the deck but leave the RCA's connected to the amp. (In turn, dodgy RCA cabling will produce ill effects due to the cabling acting like an antenna).

when they're not connected to the deck i get no signal at all

interestingly enough when we only had one rca plugged in we had some bass coming through from the deck signal but still constant interferance in the background



More elaboration on the actual problem? Does it occur when the car is moving? Does it go to the revs on the car, does it occur when the car is bumped. will it happen when the car is still? Ignition on/off etc etc... What does it sound like again? :confused:


i havent even got to the stage of moving the car yet.. still trying to get it working while the car is off... all tests have been done while the car is stationary and power to accessories only...

the sound is like a constant stream of bass that changes frequency... this is going to sound strange but say at every second it comes out with solid bass for half a second...

like an alarm clock but bass lol... does that make sence?? haha



Probably something simple... Have you checked the phase of ur subs? (if you have two)
if they play constant bass ur rca's may be shorting against 12v or the ground. Check to see the rca heads arent touching anything behind the headunit or at the amp.,


sub phase? :S meaning??? we've tried the subs on another amp and they seem to run fine...

as for the RCA's we ran them sepperatly outside the car so they couldnt come in contact with anything else.. no luck...


Grab a walkman or portable music player and plug it into ur amp. Press play and tell us what happens? Is the problem still there?

Ur amp may be screwed. Or ur rca's may be shorting out somewhere/headunit giving u grief.


tried amp in another setup and worked fine...

have to try the walkman deal tomorrow



bit of a doosy this one :(

when they're not connected to the deck i get no signal at all



Okay so the results at the moment is:


If RCA's are not connected at deck but still left connected at amp: You get no signal (obviously) and you also get no noise (that so-called interference).

If RCA's are not connected at amp but amp is activated: No noise either.

If RCA's are connected at deck and amp, but deck is off and amp is on: No results yet.

If RCA's are connected at deck and amp, and deck and amp are both on: Receiving noise.

Am I correct?


I currently think the head unit is the issue here. But need more test results.

If RCA's are not connected at deck but still left connected at amp: You get no signal and you also get no noise

If RCA's are not connected at amp but amp is activated: No noise either.

If RCA's are connected at deck and amp, but deck is off and amp is on: Recieving Noise

If RCA's are connected at deck and amp, and deck and amp are both on: Receiving noise.

Interesting :confused:

I assume you just powered the deck off, what about pulling the power cable off (or taking the fuse off) from the deck, and leaving the RCA's connected? Don't worry, try it tommorow I am going to sleep now.

Edit:

I don't think you've posted yet, but where are you grounding the head unit to? Have you tried grounding the amp to the same location as the head unit?

Give Tim's idea ago, hook up a discman to the amp and see what happens. My current diagnosis stands that the current amp and deck combo doesn't like each others grounding. This can be proven by running RCA's between the deck and amp without the outer shealth (ground) connected on each end of the RCA plugs.

i spoke to a mate who works at JayCar... he read the thread and seems to thing it is alternator whine... something to do with a diode in the alternator.. on monday im putting in a suppressor cap and some 2or4 gauge power/ground.. will have more results then :)

thanks for your help guys

justin

i spoke to a mate who works at JayCar... he read the thread and seems to thing it is alternator whine... something to do with a diode in the alternator.. on monday im putting in a suppressor cap and some 2or4 gauge power/ground.. will have more results then :)

thanks for your help guys

justin


Highly doubt that. For reasons:

a) Your car ain't even started -> Alternation isn't operating.
b) Even if its the alternator whine (which is impossible due to (a) ), it will not produce random noise, it will be similar to pink noise, and as the alternator gets faster the noise will increase its frequency.

Check headunit ground...

Where is it grounded to? Try the bolt that holds the headunit in instead.

The headunit is causing the interference.

Plug ur discman into the headunit end of the rca's see if you get any noise.

possible that the headunit ground is dodgy... will try the amp with a discman tonight when i get home... *grumble grumble lol