Australian Politics Forum - car stereo problem

freediver

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car stereo problem
Aug 6^th, 2019 at 8:06am

The CD player in my car stopped working. So I picked up a cheap portable CD player from Jaycar, with a cigarette plug thing to power it. But when I power it from the car, I get an annoying pulsing whistling noise through the car speakers. I don't get it if I run the CD player on AA batteries. The noise is there even if the engine is not running, so it is not the alternator. It is 'in time' with the spindle of the CD player. If I pop the lid open on the CD player, as the CD slows down the pulsing of the noise slows down in time with the CD. I also tried another CD player of the same make/model, a different auxiliary lead, and one of those capacitor things for cancelling alternator noise. The Jaycar people were helpful, but they have run out of ideas, though they think what I have done has worked for other people.

Any tips on how to fix it? I've looked into a new car stereo and switching to some kind of USB option, but want to stick with CDs for the moment, and it is an old car so I don't want to spend heaps of money on it.

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Bobby. Gold Member Offline Australian Politics Posts: 95236 Melbourne Gender:	Re: car stereo problem Reply #1 - Aug 6^th, 2019 at 8:16am I don't understand. The CD player has it's own speakers. How can they cause a noise in the car speakers?
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freediver Gold Member Offline www.ozpolitic.com Posts: 47352 At my desk.	Re: car stereo problem Reply #2 - Aug 6^th, 2019 at 8:26am I plug it into the car stereo with an auxiliary lead from the headphone jack on the portable CD player to the aux input on the stereo. Only the CD player and digital display on the stereo is broken. The rest of it works, and you can listen to the radio, though it is a bit difficult to navigate channels without the display.
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juliar

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Re: car stereo problem
Reply #3 - Aug 6^th, 2019 at 8:43am

It sounds like it is some sort of radiated or generated interference from inside the ext CD player.

Connecting the car battery supply might act as an antenna.

It is unlikely the speakers would be affected unless they were being supplied from an active amplifier.

You probably need one of those ferrite suppressors you often see on the external lead/s on various equipment

You would have to thread the 12 dc lead/s through the ferrite suppressor/s.

Place the ferrite suppressor/s on the 12V DC as close as possible to the ext CD player.

Another experiment would be to completely wrap the ext CD player in some aluminium foil which will stop RF radiation.

JAYCAR has these ferrite suppressors.

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Bobby.

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Re: car stereo problem
Reply #4 - Aug 6^th, 2019 at 8:46am

freediver wrote on Aug 6^th, 2019 at 8:26am:

I plug it into the car stereo with an auxiliary lead from the headphone jack on the portable CD player to the aux input on the stereo. Only the CD player and digital display on the stereo is broken. The rest of it works, and you can listen to the radio, though it is a bit difficult to navigate channels without the display.

Hi FD,
it sounds like an earth loop problem.
The headphone output is not compatible
with the auxiliary input.
Is there another output you can use?
For the cost of trying to sort it out
it would be cheaper to buy a 2nd hand
CD player from the car wreckers.

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juliar

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Re: car stereo problem
Reply #5 - Aug 6^th, 2019 at 8:47am

The car CD player probably has a stuck disk as this is a very common problem.

It is caused by grease from fingers on the CD getting on the friction pads which grip the CD and which start to slip when greasy and leave a CD stuck half way.

A CD player cleaning kit needs to be used once a month to remove the grease from the CD friction pads.

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« Last Edit: Aug 6^th, 2019 at 9:07am by juliar »

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Bobby.

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Re: car stereo problem
Reply #6 - Aug 6^th, 2019 at 8:54am

juliar wrote on Aug 6^th, 2019 at 8:47am:

The car CD player probably has a stuck disk as this is a very common problem.

It is cause by grease from fingers on the CD getting on the friction pads which grip the CD and which start to slip when greasy and leave a CD stuck half way.

A CD player cleaning kit needs to be used once a month to remove the grease from the CD friction pads.

I assume that FD would have had a go at
fixing the car CD player?

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Gordon Gold Member Offline Australian Politics Posts: 20221 Gordon Gender:	Re: car stereo problem Reply #7 - Aug 6^th, 2019 at 9:06am Try running the CD player from a different power supply, either batteries or a power lead and see what happens
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freediver

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Re: car stereo problem
Reply #8 - Aug 6^th, 2019 at 9:21am

juliar wrote on Aug 6^th, 2019 at 8:47am:

The car CD player probably has a stuck disk as this is a very common problem.

It is caused by grease from fingers on the CD getting on the friction pads which grip the CD and which start to slip when greasy and leave a CD stuck half way.

A CD player cleaning kit needs to be used once a month to remove the grease from the CD friction pads.

It has a stuck disc and several other problems. Not worth fixing.

Quote:

For the cost of trying to sort it out
it would be cheaper to buy a 2nd hand
CD player from the car wreckers.

A lot of them have security codes etc that make things complicated. If I was going to the trouble of replacing the stereo I think I'd just buy a new one.

Quote:

Try running the CD player from a different power supply, either batteries or a power lead and see what happens

It does not happen if I run it off AA batteries.

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Gordon Gold Member Offline Australian Politics Posts: 20221 Gordon Gender:	Re: car stereo problem Reply #9 - Aug 6^th, 2019 at 9:28am You could stuff around infinitum trying to filter the cars power source. Buy some rechargeable AAs from Aldi and a charger that runs off the car. Does the cars tape deck still work?
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juliar

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Re: car stereo problem
Reply #10 - Aug 6^th, 2019 at 9:33am

Bobby is very likely correct and that it is an earth loop where the ext CD player is connected to earth thru the 12V cable and ALSO thru the audio connection to the car amp.

One quick trick is to cut the earth wire on the ext CD 12V DC cable and let the ext CD player earth thru the car amp.

This may not work as the car amp may have a balanced audio input which does not use an earth except for the shield around the cable.

A better solution would be to use an earth loop isolator.

Jaycar has several of these earth loop isolators

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Laugh till you cry Gold Member Offline Posts: 13817 In your happy place Gender:	Re: car stereo problem Reply #11 - Aug 6^th, 2019 at 12:01pm The easiest way to solve this is to test it in someone else's car. If the noise is not present in another car the problem is in your car. Otherwise, the problem is in the power supply for the device. If you establish its the device you can return it for money back or exchange for another brand.
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juliar

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Re: car stereo problem
Reply #12 - Aug 6^th, 2019 at 1:42pm

LarfTillUFart,

All that has already been done except in another car which can be quite misleading depending on the earthing involved.

It is fairly obviously an earth loop issue as with batteries in the ext CD it works OK with the ext CD audio output plugged into the car amp audio input.

A quick fix might be to disconnect the earth wire in the 12V DC power lead and use the earth through the car amp.

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Laugh till you cry

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Re: car stereo problem
Reply #13 - Aug 6^th, 2019 at 3:14pm

juliar wrote on Aug 6^th, 2019 at 1:42pm:

LarfTillUFart,

All that has already been done except in another car which can be quite misleading depending on the earthing involved.

It is fairly obviously an earth loop issue as with batteries in the ext CD it works OK with the ext CD audio output plugged into the car amp audio input.

A quick fix might be to disconnect the earth wire in the 12V DC power lead and use the earth through the car amp.

There is no earth in car wiring There is only positive and negative. Negative is usually connected to the chassis of the car.

In this case, the slowing down of the CD and noise suggests a high resistance of the connection in the cigarette lighter socket. A spray of electrical contact cleaner could clean this up if it is not a severe corrosion issue.

Could also be how the negative is connected, whether wired from the battery, wired from the chassis, or just metal-metal contact of the lighter socket to the car body.

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« Last Edit: Aug 6^th, 2019 at 4:15pm by Laugh till you cry »

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Bobby.

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Re: car stereo problem
Reply #14 - Aug 6^th, 2019 at 7:05pm

juliar wrote on Aug 6^th, 2019 at 1:42pm:

LarfTillUFart,

All that has already been done except in another car which can be quite misleading depending on the earthing involved.

It is fairly obviously an earth loop issue as with batteries in the ext CD it works OK with the ext CD audio output plugged into the car amp audio input.

A quick fix might be to disconnect the earth wire in the 12V DC power lead and use the earth through the car amp.

That is one possible way of fixing it.
At least then there's only one earth.

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