After market weird stereo conundrum

[DonkeyApple]

The '72 Rangie just has a cheap, mechless stereo in it.

Parked the car a couple of months ago. Went back to it the other week and everything works fine on the stereo except there is no sound from the speakers.

Found an old head unit, connected it up and got sound. At that point I just assumed the driver or amp or something had gone on the cheap unit and ordered a new one. New one has arrived but the same issue of it working fine but there being no sound.

So now I have the mystery as to why a stereo that was working perfectly has no sound after two months of the car sitting. A new stereo shows up the same issue so points to an issue in the car not the stereo. Yet an old 90s unit still seems to work.

Struggling to think what within the car, down the line from the stereo would stop all 4 speakers from working?

[Magicmushroom666]

Could be a short to ground on one of the speaker cables, such as where they go into the door by the hinges or pinched somewhere.

I've had a stereo completely stop its output because of a fault like that, all 4 channels went with one faulty cable, probably because a lot of modern units have highly integrated amplifiers which will be all 4 channels in one internal chip.

[DonkeyApple]

Magicmushroom666 said:

Could be a short to ground on one of the speaker cables, such as where they go into the door by the hinges or pinched somewhere.

I've had a stereo completely stop its output because of a fault like that, all 4 channels went with one faulty cable, probably because a lot of modern units have highly integrated amplifiers which will be all 4 channels in one internal chip.

That sounds plausible as it explains why an old stereo gave sound but neither of the new ones do.

While the car was sitting unused the rear headlining (where the rear speakers are) was dropped to replace the rear wiper unit and that would potentially tie in also.

Thanks for that. Given me somewhere to start the search.

[DonkeyApple]

No loose speaker wires upon investigation.

Will dig out the multimeter.

[scorcher]

Can’t you just run new cable to the speakers

[DonkeyApple]

scorcher said:

Can’t you just run new cable to the speakers

If needs be but that's a bit of a faff. Would rather try and find the specific fault.

[Missy Charm]

Is it possible that the replacement, new stereo is also dud? There might be quality issues inherent to that make or model. Have you got a way of testing it away from the car in question or, perhaps, borrowing a known good 'modern' stereo and trying that in the Range Rover?

Second thought (perhaps clutching at straws) - what state is the Range Rover's battery in? I have heard of modern electronics in cars going haywire if the battery is a little on the low side and, perhaps, not providing the requisite steady voltage. If the electrical supply to the stereo is fluctuating slightly (more than possible in a seventies car if the battery is low), then it may be upset - one imagines that modern stereos are designed to be connected to the smoothed voltage supply in a modern car. Your older stereo is possibly a bit hardier, electrically speaking, so works when connected to a less than optimum supply.

Edited by Missy Charm on Sunday 27th August 10:25

Edited by Missy Charm on Sunday 27th August 10:45

[niva441]

I had a similar problem on my 89 RR. When I changed the original radio for an aftermarket unit, sometimes the speakers didn't work. Turning the headlamps on/off or adjust the electric mirrors woke them up. I cured it by adding a couple of additional earths to the back of the stereo.

[OutInTheShed]

Mute control wire?

[DonkeyApple]

Magicmushroom666 said:

Could be a short to ground on one of the speaker cables, such as where they go into the door by the hinges or pinched somewhere.

I've had a stereo completely stop its output because of a fault like that, all 4 channels went with one faulty cable, probably because a lot of modern units have highly integrated amplifiers which will be all 4 channels in one internal chip.

Modest step forward today. Plugged in the very old stereo and went round checking each speaking. Rear near side isn't working.

This would tie in with your thought re modern stereos.

This is also the area where the rear wiper is which was replaced between the period when the stereo worked and when it didn't.

[DonkeyApple]

Back to square one as of yesterday as all lines to speakers are working fine. Most odd.

[DonkeyApple]

Magicmushroom666 said:

Could be a short to ground on one of the speaker cables, such as where they go into the door by the hinges or pinched somewhere.

I've had a stereo completely stop its output because of a fault like that, all 4 channels went with one faulty cable, probably because a lot of modern units have highly integrated amplifiers which will be all 4 channels in one internal chip.

All fixed. Managed to source an old stereo to test each speaker in turn. It was the near side rear speaker as first thought during the original test. The cable was pulled back through to reveal it had been pinched when the rear wiper was being replaced. Taped back up and all works fine.

Thanks.