P38A Hifi peeps update!!

biketeacherdave said:

If you have a dsp amp and it does you wont get anything to work unless you do what I did which is why I think you have door amps

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Brain beginning to meltdown now, so I'll pick up on this tomorrow and physically check out hardware and what is/not working.
Thanks for your time.

biketeacherdave said:

Nice effort, I did this in mine

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Now your just bloody showing off, multi media wizardry!!!

The only issue I've found today was what sounds like an earth buzz, but it goes as soon as the car has completely shut down and will start again when the ignition is turned back on and running. Weird, the adaptor has a circuit that is supposed to cut earth buzz. I've adjusted the potentiomèters most of the way down to try and eliminate the buzz ( which is nigh on detected) but there.. even when the stereo is turned all the way down to 0 volume.
After a minute of the ignition shut down the buzzing stops completely.
Question, when the sound system and ignition are turned off, do the amps shut down immediately or shortly after?
Also the only thing I did differently this time was I joint the sub amp earth to the stereo earth instead of it's own earth.hmmmm.

Thought this might happen. It would help to know what the circuit inside the InCarTec box actually does, but feeding blanaced inputs from attenuated speaker outputs will always be a compromise. Things to check:

• Is the buzz present with ignition on, and engine off ? If the buzz is only present with engine running, then it will require plenty of debug effort to find the culprit.
• Is it on all speakers of only some ? Open the doors & listen to each in turn to be sure.
• Check that pin-6 on every door amp is properly earthed.
• Check C207 & C351 (left footwell), and C208 & C301 (right footwell) are not corroded and making good contact.

The door amp balanced inputs (pins 9 & 10) expect correct signals on each +/- wire pair. If one side is bad, you will still get some audio but loads of buzz.

FYI, here's the circuit I use to feed each Line Output on the head-unit to the balanced inputs on the door amps & sub amp. No hum, buzz, hiss, etc. Also has the advantage that the balancing cancels out interference induced within the wiring looms.

Right then,
If I get in the car and turn the radio on with out volume, no lights and ignition it buzzes.
Then after a minute it'll stop buzzing.
With the ignition off and nothing else turned on I then push the hazard light switch it'll start buzzing and then go off after a minute.
Almost like the car is woken up, buzzes the stereo and then goes back to sleep when nothing else happens .. and stops buzzing the stereo... Who said they don't have a mind of their own!!!

Assuming when radio is on with ignition off you are in P1 on key (i.e. aux power only) ? Radio should only have power in P1 & P2, and not in P0 off position.

The issue sounds like BECM talking to something, and the data wiring interference to the door amp feeds. Not sure why Hazards cause interference. The switch is a simple on-off to BECM, which then switches the indicators on-off.

• Do a really thorough re-check on radio & door amplifier earth wiring.
• You could try adding new earth wires to the radio and all door amps to a common chassis ground point. This then bypasses any splices in the looms that might be faulty.

Also please use terminology P0, P1, P2, etc for ignition switch, and "engine running / not running" . . .makes it easier to understand the conditions.

Got it,
P0 on the key and engine none running.
It does sound like the becm is busy and the earth does sound even more relevant. The last stereo didn't do this but wasn't as sensitive either.
I think earthing the sub to the radio earth may be a possible culprit. Last time it was earthed on a supplied earth in the loom. It is the only difference in the installation I've physically made other than the high low adapter.

Ok, another thing.
The older setup with the Kenwood didn't use the orange wire on the power and earth plug on the car wiring loom. The new JVC does? Do you think that could be the change. As I say the Kenwood never suffered from the issue.

Aha, could I make something that could stop any noise in the positive feed to the radio or the negative feed.
It seems really odd that the only things that have changed are the stereo head unit and an adaptor.. this is getting way too involved for my none sparky head

What year is P38 ? My RAVE shows Red-White for the main 12V feed, and White-Pink for the ignition switched 12v feed. P0 position on ignition should not allow radio to be powered on. Standard wiring requires P1 or P2 for the radio to work ?

You could fit filters in both 12V feeds to the radio, but most modern head units usually have good filtering built in. The problem is most likely bad earths or interference in the balanced feeds to the amps. Remember neither the "resistor circuit" or the Incartec adapter provide proper balancing to the door amps.

She's a mid/late 99.

The yellow and red wires on the head unit are joined to the yellow feed from the cars loom.
It allows me to turn on the radio without having keys in. The Kenwood was the same.
I'll look in the info give on the Intex adaptor as well.

OK, 12V understood. With the ignition in P0 & radio on, the only ECU that should wake up are BECM, and EAS. Filtering the 12V is really only good for Alternator & other engine related noise, which you don't have because engine not running !!

If the Sub feed is wired to an RCA Line connector, then you have potentially un-balanced the feed. I did this with my old Pioneer stereo which had RCA for all 5 outputs. Didn't use speaker outputs !! It worked but there was some low level buzz, albeit not audible with radio turned up. So is the Sub buzzing the same as the doors ?

I still say connect temporary good earths to radio & all amps, bypassing the loom splices (these are hard to locate & the soldering has been know to break down over time). Then report back.

Pete

List to do.
Check for sub buzz,
I'll redo an earth for the head unit first.

If that doesn't cure it, I won't go taking the door cards off to find earth points and wires. I really don't want to disturb the plastics and the clips and so on.
Could new earth's be supplied to the doors main wiring plug or preferably right at the door amp
earth points?

to prove the problem, it's best done at the door amps. Run a wires directly to same ground point as the radio. Otherwise you still have various connectors & splices between the door amp & chassis earth. Once you prove where the bad earth is, then you can either install permanent new wires, or fix the bad earth !!

Earth loops can cause buzz as can alternators.