Stereo's gone nuts - Tech heads please help

[sgt_nemesis]

Howdy all... Long post inbound!

Ok here's the problem. I'm running a Pionner Premier DEH-P860MP Head unit.

It feeds a 4 channel amp and a bridged 2 channel amp, both mid quality brands you don't get in the US. I've had them for some time, and have used them on my new set up as a go between till i get better amps.

Anyways, everything was working fine. Nice sound, no feedback etc etc... I've built plenty of simple systems.

So, i'm away 4WDing on the beach, and while everyone is packing up camp in the morning i'm sitting in the 4WD which is not running listening to the sounds. Then when we're leaving i start the truck and the stereo goes ballistic! The speakers were popping, like they were playing a beat, and it started screaming some massive electric sounds that pierced the eardrums almost.

I tried a few things to diagnose it. I ended up chasing it back to the sub amp, in which i thought it was a loose ground/earth wire. So i fixed that, and turned in on to hear the same sound. So i pulled the power from the sub amp and everything went back to normal (no sub, but with it going it effected all the speakers not just the sub)

So me figures something chewed out that amp, even though it has it's own fuse which was unnafected. But then about two days later i start the car, and now i've got ignition feedback through the speakers. You know, like the cheap system we first built, it whines with the revs, and turning on the head lights make it worse etc.

Now i'm wondernig if anyone has any suggestion to what has gone on? One minute all is good, no feedback, everything works, then i lose an amp (maybe), followed by an addition of signal interference. Surely it couldn't be the amps like that? And it can't be the signal, the HU puts out 6.5V and i've run the RCA's away from the old power cable myth..... Oh, and both problems have followed a physical starting of the 4WD.....

Any ideas? Any questions to further predict it?

I'm also wondering, in the meantime, if i run the HU directly to the battery instead of an ignition source; will that stop any ignition feedback?

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[sgt_nemesis]

Update: I just re-tried the sub amp only using one channel, and it turns out that either the R or L channel is stuffed, the other is fine.

So that brings me to the ignition feeback.....

 

[caddy39 10+ year member]

Seems you and I both have problems with the same HU. Seems no one out there likes to help us out. I have a DEH-P860MP that doesnt even turn on anymore. Have you ever had that problem? Anyways man, good luck.

 

[Logikalliquid 10+ year member]

Running the HU power directly to the battery instead of a switched source, like the ignition, may drain your battery. Maybe you can find a different switched source? I wish I had more help for ya, but at least I'll bump you to the top of the page.

 

[sgt_nemesis]

Well touch wood it hasn't not turned on before. I'm stoked with the HU, but want to lose this whine. One of the reasons i bought a unit with such high output was to insure no interference.

On the other note, would the HU draw power when the face is taken off? I would assume it wouldn't as the amps etc aren't on till the HU is... Even so, without trying does anyone know if that would prevent the ignition feed back?

 

[johnecon2001 5,000+ posts]

try regrounding the HU to the frame, clean off the old ground.

Do you have the RCA's looped from one amp to the other? or two different sets, one to each amp. if they're looped the output on one amp may have gone bad.