Headunit interference

[Goldie 2]

Ok, i purchased a second hand head unit not long ago and a mate of mine did the honours and whacked it in the car..

 

All seemed good at the beginning but now it sounds terrible, i get interference noise in the speakers and loud noise when pulling main beam on. Im not sure if the beam did this originally as i havent really used the car much but now its all over the shop. Worth mentioning this happens with the radio or Cd player running..

 

Im intending on pulling the radio back out later today but does anyone have any suggestions, bit awkward as it was a favour from a mate but i think it must be something to do with the fitting...

[Toad 0]

Probably wants one of thise things that I can't remember the name of in the main power line. do you know how he connected it?

[Goldie 2]

Im not too sure mate, ill whip it out later on and see whats going on..

[nemesis360 0]

ill whip it out later on and see whats going on..

 

Are you sure you want to say that to Toad? :lol:

[Toad 0]

ill whip it out later on and see whats going on..

 

Are you sure you want to say that to Toad? :lol:

 

Good point.... I'll get the lube and special trousers on just in case. :pharoh: :new-bday: :fondle:

[Jim Bowen 1]

if its "built-up" isn't that normally a sign of a bad earth?

[zak 0]

i'd go with the bad earth theory as well.

[Goldie 2]

Cheers for the input fellas, gonna have a cuppa and then ill start the investigation..

[Goldie 2]

Right ive had a look and...i dont know what im looking at..

 

The red and yellow power wires have been swapped over and it powers up correctly and holds its memory.

 

When people say bad earth where abouts does the radio earth on to?

[junkie 0]

The red and yellow wires are correct swapped over, thats how mine is and as you say it holds its memory.

 

If it was a really bad earth it would cause it to trip on and off too.

 

Think Toad is on about a noise suppressor.

 

Is it the usual whining noise you get when you have an amp (i know you dont) when you have the power cable running net to the RCA or speaker cables and goes higher pitched as the engine revs get higher?

[Goldie 2]

Erm, im not sure if it relates to engone speed. It makes noises though when wipers are switched motor is switched on and switches off and on main beam when the car running it sounds terrible. If i flash the main beam without the egine running the headunit trips..

[junkie 0]

Trips off the power or trips the fuse.

 

I was trying to figure out the noise type and if it did it with engine speed you would know what i mean.

 

Does sound like a bad earth then, just try a new earth wired in whilst the head unit is out just wired randomnly to a good known earth point to prove it right or wrong. Then if it is better just run a new earth all tidy, ideally you want straight onto metal not paint.

[Goldie 2]

It just trips the headunit, it has a little think and then comes back..

 

I cant work out which is actually the earth lead, im not going to lie, i know bot all about car radios..

[junkie 0]

It must be a bad earth then as my amp when 1st installed kept doing the same thing too, off little think then on.

 

I may be wrong but it could be the brown wire on the cars original wiring not the head unit, there is lots brown wires in there, and they are earths, but off the top of my head i cant remember what wiring goes to the headunit.

 

You should get 12v between the brown earth and either red or yellow power lead 1 with ignition on and the other permanent live.

[zak 0]

as junkie says while the head units out temporarily run an earth wire to see if it solves the problem. I had a similar issue with an old alipne unit i installed in my last corrado.

[Goldie 2]

Right, sorted..

 

Had a bit more of a fiddle around and there were 2 phono leads in the back that are for the interchanger. There isnt a port for the main wire thats needed to run the changer, i pulled the phonos out whilst messing about with it, tried it and it was fine, put them back in and it tripped again. Ive taped the phonos up and secured them out of harms way, also tidied everything up that was in there and shes as good as new, no tripping or interference in the speakers at all..

 

Guess the main beam (worst offender but wipers did it slightly) was messing about with the power through the interchanger which is earthed so you were quite right fellas..

 

Hope that is the end of the problems, PM coming your way Junkie about speakers...

[junkie 0]

No worries but still not got 1 :wave:

[skinnyman9000 0]

The red and yellow wires are correct swapped over, thats how mine is and as you say it holds its memory.

 

If it was a really bad earth it would cause it to trip on and off too.

 

Think Toad is on about a noise suppressor.

 

Is it the usual whining noise you get when you have an amp (i know you dont) when you have the power cable running net to the RCA or speaker cables and goes higher pitched as the engine revs get higher?

 

I get this, slight interference that alters with revs, was told it could be a dodgy RCA connection.

[junkie 0]

Definately not dodgy connection if your running an amp.

[skinnyman9000 0]

Running an eton amp in the boot.

 

Im thinking its something to do with the headunit connnections. If you push the right hand side of the headunit it gets quieter, which leads me to believe some kinda of loose cable or metal connection somewhere, hmmm

[junkie 0]

Maybe but it is usually 99% of the time the main amp power cable thats too close to the RCA or speaker cables, mine also does this too and i cant get rid of it, but if you saw the amount of wiring in mine and how unaccessable it is then you would understand why i leave it, mine i can hear it at lower volumes but when i turn it up the volume cancels it out, and as i only have 1 volume setting, LOUD, then im happy to leave it, otherwise it means taking the whole rear install out, rearranging the cables again, putting it all back together and it still not been right, done it that many times now i can uninstall and reinstall in 2 hours.

[borarob 0]

Maybe but it is usually 99% of the time the main amp power cable thats too close to the RCA or speaker cables, mine also does this too and i cant get rid of it, but if you saw the amount of wiring in mine and how unaccessable it is then you would understand why i leave it, mine i can hear it at lower volumes but when i turn it up the volume cancels it out, and as i only have 1 volume setting, LOUD, then im happy to leave it, otherwise it means taking the whole rear install out, rearranging the cables again, putting it all back together and it still not been right, done it that many times now i can uninstall and reinstall in 2 hours.

 

 

have you tried using a ground loop isolator on the RCA's going to the amp. whenever I do an amp install i stick those on as a matter of course. I always run the power and RCA's together (cos I'm lazy) and have never had interference (apart from the first time I installed a multi-amp system which was what caused me start using the isolators in the first place)

 

IIRC they are a few quid from maplins.

[Guest]

Glad you got it sorted. :clap:

 

Slightly off topic. Goldie - remind me, what trade are you?? :norty: :?

[Goldie 2]

Glad you got it sorted. :clap:

 

Slightly off topic. Goldie - remind me, what trade are you?? :norty: :?

 

Not a car headunit maintainer Judith.. :wink: Im used to nicely layed out large electrics - not snakes weddings in car dashboards...

[timg60 0]

[not snakes weddings in car dashboards...

 

I know how you feel. I am sure my electrics are an accident waiting to happen. DDI dials, Illuminated Knob, I-pod adaptor, 12v power out & boost guage. Its all a little bit scary behind the dash but it all works so I dont want to touch. TBH I should really pull it all out and rewire it all properly.

They all have inline fuses though so should be safe from fire :nuts:

 

Note to self " must get a fire extinguisher"......