Ground loop noise

[Kevin Bacon 5]

Well I spent 4 hours rewiring it tonight.

 

Both preout leads now run down the side of the transmission tunnel.

 

The earth has been moved to the M6 bolt welded to the nearside rear 1/4 panel.

 

The preout leads have been trimmed of all excess slack and the phonos resoldered.

 

The bonnet EMI suppression strap is present and connected.

 

All joints have been soldered.

 

I am 100% happy the installation is not at fault.

 

AND......the bloody noise is still there :x

 

I'll try the isolators tomorrow and if they don't solve it, I'll rip it all out and fit an Alba midi-system instead.

[Henny 0]

get a ferrite ring mate, stick it over the RCA cables and see if that makes a difference, or get an iron curtain ring and run the RCAs through and around it (single wrap, thru the middle, around the outside and back thru the middle again....) it's amazing how much noise you can knock off doing that! ;) 8)

 

Lemme know the outer diameter of the cables, and I'll lob a couple in the post to ya! ;)

[G60Jet 1]

Nige, where's the best place to earth at the back? There's something rattling behind the rear card actually, so is in there a good place to earth?

 

Randal, they're were £15 each mate. I needed two unfortunately as it's a 4 channel amp :cry:

Best place if a cable to the battery mate, but like i said there are earth points in the boot and behind the rear quater trim, they are basically plastes with loads of connectors for spade terminals

[Kevin Bacon 5]

Cheers Henny mate, the cable diameter is 6mm. My address is the mod area :wink:

 

You're a star!

[Henny 0]

I'll see what I can do in the morning... 8) Pretty sure I can go upto 10mm... :D

[G60Jet 1]

have you checked the noise supressor in the altenator is ok?

I had bad noise on my stereo till i changed the brushes on my alternator, now im 99% sure the noise supressor is the other little wired on thing on the alternator. Change them both, the brushes only cost a around 5 quid iirc.

 

If you are running an amp you should have it earthed back to the battery via a low impeadance wire, if not try running the earth back to the battery, not the chassis earth point in the boot.

 

you could try this too, got idea to change the brushes anyway!!

[Kevin Bacon 5]

Can you change the diode packs on VR6 alternators? I thought they were sealed units? They certainly look it anyway.......and a bastard to get to :x

 

It's nearly 100,000 miles old, so could probably due with a regulator refresh.

 

Ho hum, the joys of doing a job on a Corrado that invaribly turns into 10 additional jobs in order to complete the first job :?

[G60Jet 1]

 

Ho hum, the joys of doing a job on a Corrado that invaribly turns into 10 additional jobs in order to complete the first job :?

 

yeah but they'd need doing sooner or later anyway, so best only getting your hands direct once instead of 10 times!!! think of all the money you save in hand cleaner!! lol

[Kevin Bacon 5]

True!

 

I tell you what, these past few days have been invaluable in terms of replacing missing screws and clips etc. The car feels a lot tougher inside now with fewer rattles :lol:

 

Oh it also received it's first hoovering session in 18 months :-P

[Guest]

Hmmm, shame you didn't post that earlier before I bought the darn things! Nevermind!

 

sorry mate, don't really read this section as I haven't got the cash to sort my system atm, and its all too painful reading about the nice systems everyone has installed.

 

I have a rather nice Rockford sub sat in my room, just need an amp, and then I will start to install my kit

[Henny 0]

Cheers Henny mate, the cable diameter is 6mm. My address is the mod area :wink:

 

You're a star!

 

It's in the post now... look for the dodgy looking matt black gaffa tape'd box! ;) :lol:

[Kevin Bacon 5]

LOL, cheers Henny, you're a true gent :lol:

 

Unfortunately they're not required now as I traced the source of the noise to the damn head unit. The front and subwoofer preouts (surface mount phonos) clearly have a poor earth. The rear pre-out (fly lead) is silent, with both RCA leads.

 

Can't bloody believe it and the worst thing is I think it's out of warranty now :x

 

So my choices are now using a Y splitter off the rear output but I'll lose the Fader and crossovers or take the sodding thing apart and do some *proper* soldering on the motherboard.

 

Or I could just bin the thing and get an Alpine instead.

 

Thanks for all your advice and help guys anyway. All this has rejuvinated my interest in ICE again and all the panels and trims are now secure, so at least there's some positives to this saga!

 

K

[Kevin Bacon 5]

Just had a thought acutally...... my amp can take line level and speaker level inputs. Since the headunit is quiet with the speaker outs, what do they sound like in comparison to preouts? Obviously there is some sort of high impedance resistor network inside the amp which reduces the current, but I've never used speaker outs as it's always struck me as being a bit bodgey?

 

K

[coolrado 0]

Just had a thought acutally...... my amp can take line level and speaker level inputs. Since the headunit is quiet with the speaker outs, what do they sound like in comparison to preouts? Obviously there is some sort of high impedance resistor network inside the amp which reduces the current, but I've never used speaker outs as it's always struck me as being a bit bodgey?

 

K

in my experience it usually sounds awfull when run from high level outputs you could just try having an external earth to the phono screen and ground it to the head unit casing

 

really expensive audiophile grade phono cables use this method or sometimes have a seperate screen covering both cables which is grounded at one end

 

try your local home hifi specialist there is no reason not to use home phono cables as most of the ones you get from the likes of halfords are not up to much (usually cheap crappy phono cables with thicker insulation to make them look expensive)

 

the same goes for speaker cables i used QED silver spiral something like 50% silver copper mix and a damn site better than the crap from halford and maplin and you can get it in a 4 wire type (neater and quicker to run down the car) and it does make a noticeable difference

[Kevin Bacon 5]

Cheers for the advice Coolrado. Yeah I've learnt that lesson in the past about cheap phonos, which is why I went for some decent £50 each ones this time round. Yeah I could try the grounding to the chassis trick but to be honest, I shouldn't have to really. It's all supposed to be plug and play and customers shouldn't have to faff around with cables to get a good S/N ratio. Especially not when Pioneer boast of it's excellent in-built noise suppression...... yeah right!

 

Well the good news is I found the original invoice and I have 5 days left on the warranty! Talk about cutting it fine!

 

I'll get a replacement unit I think, or chop it in for a better quality unit.

 

And here's another question...... can you buy amplifier-less head units? I.e. just a CD drive and processor with line level outs only? I just don't like the heat these head units produce these days. They get hot enough to cook food on, which is never good.

 

K

[coolrado 0]

And here's another question...... can you buy amplifier-less head units? I.e. just a CD drive and processor with line level outs only? I just don't like the heat these head units produce these days. They get hot enough to cook food on, which is never good.

K

pioneer and alpine used to do these TRANSPORT ONLY head units years ago and they still might quite expensive iirc, but the quality was far better than an all in one system no internal amp circuitry but the case was still full inside using bigger higher quality components

you can turn the internal amps off in my pioneer and yes it does run much cooler but i am running my fronts of the head unit at the moment due to a lack of a spare amp

 

total car audio magazine is a good place to look usually covers the higher quality (and price unfortunately) end of the car hi fi market or try e-mailing them for advice i have a couple of times and had my e-mails printed in the mag as well

[Henny 0]

yup, Nakamatchi also make 'em and I know that Clarion used to, but I've no idea about their current line up... 8)

[Kevin Bacon 5]

I don't think my DEH-PM77MP has the facility to turn the amps off :cry:

 

I rang the stereo shop where I bought it from and they said they'd have to send it off for repair. Well if they're going to do that I might aswell repair it myself and sever the amp connections internally at the same time!

 

I'll see if I can get a refund because I don't see why I should have to be stereo-less for 3 weeks due to a fault. They should give me a new one or a refund imo.

 

Or is that unreasonable?

[coolrado 0]

Or is that unreasonable?

not unreasonable just very unlikely :roll: :lol:

might be worth having a fiddle when it comes back from repair most places have a policy of 3 repairs = replacement thats what i did with my phone :lol:

[bcstudent 0]

I think that sort of service is pretty standard from most re-sellers. Your chances of getting a refund that close to the end of the warranty period are slim to non-existent. I believe refunds and goods exchanges generally only take place in the first month or so. I'm having the same problem with a knackered Asus motherboard at the moment. As I'm eight months into the warranty the re-seller I bought from is only prepared to sent the faulty item back to the manufacturer on my behalf for repair....a procedure that could take up to six months to complete!

 

If you're sure of the fault then you may as well attack it yourself in my opinion. I certainly would.

[Kevin Bacon 5]

Yeah, given the warranty is almost up, I may aswell have a go at fixing it myself. I have no faith in a repairer finding the fault! I think a solder joint may have become dry due to the excessive heat these things produce.

 

The surface mount Phonos are a pain in the arse anyway as the radio then rubs on the upper heater pipe, causing a constant creaking noise. So the plan is to dispense with surface mount jobbies and replace them with fly leads.

 

I will also run the HU straight off the battery too, in case noise is being introduced via the switched ignition feed.

 

K

[Kevin Bacon 5]

Headunit was the cause. They've sent it off for repair, so I've got no tunes for a couple of weeks now :cry: