engine noise through radio

[ozy1]

as above, i get engine noise throught my radio,

truck is a Patrol with TD42, it started all of a sudden, and cant pin point why, nothing eletrical has changed to casue it, radio has been in the truck for 3 years,

i think its coming throught the amp, i have tried different amps, also re run new the RCA cables casue i thought they might have been a bit close to the Power, but the power cable has always been at least half a metre away,

i have tried jumper cables between amp earth and battry, also between chassis and body, and body and battry, and battry and chassis, and it still continues,

any help appreciated,

Shawn

[-Scott-]

Any wierd behaviour from your charge light recently?

Could be alternator brushes on their way out, causing minor arcing syncronised with engine speed. Disconnect your voltage regulator (should interrupt field current?) and see if noise disappears.

Hopefully somebody will highlight any flaws in my theory.

Scott

[DamTriton]

also bad earth, batt terminal-chassis

[Oscars]

maybe power feed running to close to leads etc

[ozy1]

Alternator is charging fine, it was rebuilt approx 6-12 months ago,

power leads and RCA's are run far enought apart, as i actually seperated them further then previous, and it didnt change, i was thinkin bad earth as well, so i made up some new earth leads and will fit them asap and see how i go,

thanks guys

[RAY185]

If that doesnt work check that the noise supressor on the back of the alternator is still intact/connected (it looks like a condensor). If it is try fitting a new one (they are cheap as chips) and see if that corrects it.

[smiley_smoke]

jaycar have noise filter for about 30 bucks. i heard they do the trick. my zook doesnt get any engine noise at all.. gues the hamster is running fast enough in my zook

[F'n_Rover]

Is the power feed direct to the battery ? Could help.

[Woop]

Having had this problem a lot before on my TD42, if your earths are all sound and the suppressor on the Alternator is ok, it can be brushes and or a bad diode in the diode pack. Usually you'll see this last one as a very dull CHARGE lamp and high Alternator voltage. Sometimes the seal between the vacuum pump and Alt wears, allowing engine oil to leak onto the slip-rings--even though theere is an oil drain hole provided...

Nick

[ozy1]

okay, done a few checks, earths have all been double checked, and some even replaced just in case,

now, the noise suppressor, went looking for one and couldnt find it attached to my alt, so i bought one, now how do these hook up, and to what terminals?

all help appreciated,

Shawn

[ozy1]

anyone please?

[84ZOOKSTA]

it just mounts betwen +ve and Ground on the back of the altinator.

Eg. The small bracket mounts to ground (terminal on the altinator) and the small wire to the +ve (charge terminal)

Cheers
Simon..

[ozy1]

thanks mate, much appreciated,

[ozy1]

okay, fitted noise surpressor, and it hasnt fixed it, any other ideas? please its driving me insane

[84ZOOKSTA]

I had this problem in my Nissan Skyline, I did all you have done and had no change.

So i went and bought a "Ground Loop Isolator" from Jaycar. it goes inline with the RCA leads and it fixed it. No noise after that.

Cheers
Simon..

[ozy1]

I had this problem in my Nissan Skyline, I did all you have done and had no change.

So i went and bought a "Ground Loop Isolator" from Jaycar. it goes inline with the RCA leads and it fixed it. No noise after that.

Cheers
Simon..

any idea why it would start all of a sudden thou, considering the stereo has been in there for 2 years or more?

[DamTriton]

I had this problem in my Nissan Skyline, I did all you have done and had no change.

So i went and bought a "Ground Loop Isolator" from Jaycar. it goes inline with the RCA leads and it fixed it. No noise after that.

Cheers
Simon..

any idea why it would start all of a sudden thou, considering the stereo has been in there for 2 years or more?

Bad earth IN the head unit/amps from vibration, maybe?

Could be a crack in the PCB earth near the output of the head unit/inputs of the amp. I would say if you have excluded everything else outside the head unit/amps, then logically it has to be something inside it. If you can work out bu substitution whether it is the head unit or the amps and then take the offending unit to a repairer.

There are a number of other things internally that it could be (drying out electrolytic capacitors for one), so it may cost a bit to find/fix by a service agent.

If the two amps that you tried still made the buzzing then it is likely to be the head unit that is at fault.

[-Scott-]

Get your alternator brushes checked.

A capacitor will "smooth" some high frequency noise on the 12V output, but that's not necessarily your problem.

Sparks are wideband RFI (radio frequency interference) transmitters. If your alternator brushes are sparking, they're transmitting wideband RF noise. It's very hard to predict the precise form of this noise, or where it may be "demodulated" into an audible signal - but it will be engine speed related. A capacitor on your alternator output won't affect this noise.

Disconnect your regulator and you should stop current flowing through your brushes. No current = no arcing.

[DamTriton]

Get your alternator brushes checked.

A capacitor will "smooth" some high frequency noise on the 12V output, but that's not necessarily your problem.

Sparks are wideband RFI (radio frequency interference) transmitters. If your alternator brushes are sparking, they're transmitting wideband RF noise. It's very hard to predict the precise form of this noise, or where it may be "demodulated" into an audible signal - but it will be engine speed related. A capacitor on your alternator output won't affect this noise.

Disconnect your regulator and you should stop current flowing through your brushes. No current = no arcing.

You would expect that interference to slowly increase in amount over time. His issue was that it suddenly occurred.............

[-Scott-]

Get your alternator brushes checked.

A capacitor will "smooth" some high frequency noise on the 12V output, but that's not necessarily your problem.

Sparks are wideband RFI (radio frequency interference) transmitters. If your alternator brushes are sparking, they're transmitting wideband RF noise. It's very hard to predict the precise form of this noise, or where it may be "demodulated" into an audible signal - but it will be engine speed related. A capacitor on your alternator output won't affect this noise.

Disconnect your regulator and you should stop current flowing through your brushes. No current = no arcing.

You would expect that interference to slowly increase in amount over time. His issue was that it suddenly occurred.............

Perhaps the brushes suddenly started arcing. Got mud?

[ozy1]

thanks again guys, will have to pull the alt out after nissan trials, and check them out as i wont have tiome this week, will see how i go

thanks again