Car audio help

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xpd

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#317789 15-Nov-2024 09:03

I have a JVC head unit in my car which was installed new when we got the car. "Basic" double DIN, CD/radio/MP3 - Speakers are the factory units. No amps etc.

Has been working fine over the years, but have noticed lately that if I crank up the volume, the unit shuts off and then on again. If I leave the volume up it keeps shutting down, so I have to quickly adjust the volume down soon as it comes back.

Obviously I'm pushing the limits on something to cause this, but what exactly - head unit limit ? Speakers causing some issue to feedback to head unit (but doubt it) ?

Gavin / xpd / FastRaccoon / Geek of Coastguard New Zealand

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djtOtago

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#3309265 15-Nov-2024 09:57

1) The unit's internal Amp is overheating. Thermal past is old. A component has come loose from heat sink etc.
2) Unit's power supply / regulator has become unstable.
3) You have a speaker that has developed a fault. With high volume, the speaker coils appear as a short to the unit's amp, so it shuts down.

I would start looking at the speakers first. Try running the unit with the balance all left or right and or all front or back and see if you can isolate a bad speaker.

xpd

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#3309304 15-Nov-2024 10:43

Cheers, will give that a go this weekend :)

Gavin / xpd / FastRaccoon / Geek of Coastguard New Zealand

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Goosey

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#3309347 15-Nov-2024 12:55

Might be as simple as a loose or broken wire…. Either ground or power.

it could also be the wire and connections to the speaker at the head unit end being loose or broken strands.

id start with checking the wire harness behind the head unit but be careful when pulling out as there might be not much slack (hopefully the installer used a decent connector).

gut feeling its about power / grounding. Any other noise?

Goosey

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#3309360 15-Nov-2024 13:02

Side note, in my youth I spent hours on car audio. At least once a year I’d cut and recrimp the power and speaker connections…..certainly heard difference.

hsvhel

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#3309366 15-Nov-2024 13:12

Classic grounding issue for the deck, I'd be putting my money on that

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tripper1000

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#3309403 15-Nov-2024 15:47

I second the bad/loose wire theory.

When you are nearing the danger zone, do the stereo backlights start dimming?

If the main earth was bad and it was getting an earth through the antenna connection (or RCA or camera wire) instead, it would run OK at low power levels but fall on its face once you cranked it up.

This can also be caused by the earth wire deeper in the cars wiring failing because someone messed with it, or the bolt/terminal went rusty etc. I've found non-conductive factory earth terminals that were painted and I couldn't see how it ever worked to begin with.

Also give the fuses a wiggle (remembering there is probably fuses on the back of the stereo as well as the cars fuse box). I've seen slight corrosion on fuses cause this kind of behaviour.

If it was a speaker or speaker wiring fault, you'd hear it at lower volumes (not working, bad distortion etc).