aftermarket stereo possible grounding error?

[Jace]

i have an intermittent stereo issue, the head unit's a JVC KD-Gsomething with alpine 6"'s and tweeters.
as far as i can tell, the wiring is the original mazda stereo wire.
just wondering if NA6CE's are known at all for the stereo wiring playing up after a while.
problem is that occasionally on startup the left speaker (or maybe tweeter) crackles and cuts out the power from the head unit to all the speakers.
i recently wired in a second JCV harness in hope that the issue would be the harness itself, but that hasn't helped at all.
had a bit of a fiddle with the connections to the left door speaker and i think i've made the problem a bit more acute (fractionally more reliable, in that the on/off intermission isn't as definite now) so i might drive somewhere with music, park and whatever, then start up and drive off without music. then repeat the park and cut the power, only to regain my music on a second start up.
so i figure there's a loose and bare wire touching on something it shouldn't be.
although the music will only fail to return after i stop the car and turn off the ignition, then re-start, rather than cutting out immediately when i hit a bump in the road.
so i dunno.
guessed i'd ask here before taking it to an auto elec. and spending money i don't have, because most of you are probably quite practically minded.
reading over what i've just written makes me think that the headunit could be to blame.
i hope it isn't, and any help would be great.
thanks.

[marcusus]

Ergh... cable faults are the hardest to trace...

The only bit of advice I can offer (which may well not help either) is to try and buzz out the speaker cable to see whether or not you have continuity. With a multimeter, set it to detect continuity (the "ohm" symbol usually, or if your multimeter is so inclined, go around the settings whilst touching the probes together... when you get an audible beep/buzz, that's the one you want). Take out the head unit and the speakers so you have access to all the wiring. Short the speaker wire together at one end, then place the probes of the multimeter on the other ends and see whether you get continuity. If you get intermittent continuity, then you may have found the problem.

However, by the sounds of it, it seems like it's not gonna be easy to find, since you're getting sound intermittently.

[Jace]

yeah either way i'm definitely not looking forward to it, thanks a heap though.

[cshaks]

It's a long shot, but you could perhaps try cleaning all the connections with some fine wet and dry paper?
I realize that you have a new harness in, but I have seen some pretty weird things happen with some crud or corrosion in a spade connector....
Might be worth a try, and costs nothing.

Cheers
Chris

[philz]

What are you using to connect your wires to the speaker connections? Spade, or directly soldered on and heat shrink?

It sounds like you have a short somewhere.

[Jace]

What are you using to connect your wires to the speaker connections? Spade, or directly soldered on and heat shrink?

It sounds like you have a short somewhere.

directly soldered.
i re-soldered the left (crackling on start-up) speaker connections today, worked for a couple of minutes, until i turned the car off.
then on re-start, the same crackle and then nothing.
confirmed it is the 6" speaker, not tweeter.

if there was a wire shorting somewhere, the crackling sound from the left speaker would hint that it's that connection, maybe even speaker that is the problem, yes?
if this is the case, would this problem wire/connection trip out all power from the headunit to the speakers? is that exactly what would happen in the case of a wire shorting somewhere?