CD player interference

[jrz126]

I had a problem with the cd player in my car a few months back, somehow the internal amp burned up, but the pre amp outputs still work, so I can still use the cd player but I just have to have external amps.

Anyways, I'm getting interference from the alternator now (a whine that is proportional to the engine RPMS). I'm pretty sure that the interference is coming through power wires for the cd player. Anyone know of a filter I could build/buy (build preferibly) to try to condition the signal? (I already bought a filter for the RCA cables and it didnt work, and my rca's are away from the power wires too.)

 

[bmcculla]

You could try putting some ferrite beads on the leads from the alternator.

Also try checking out your battery. I had the same problem in my car and it turned out to be a nearly dead battery.

 

[jrz126]

i dunno about putting them on the alt. wires. maybe just on the power wires for the head unit? Thats all that i need to filter (i think) so it wouldn't need to be a high power filter. I recall reading something about a choke filter, would that work for this?

 

[williB]

its the ignition coil that you are hearing ( i would bet )
i wouldent think that the noise is comming through the CD power wires, because i assume that it wasnt making the noise before the Amp blew up?
i would suspect that the noise is comming from the External Amp, or the wires coming from the preamp to the amp. they are shielded ?
you might have a bad ignition wire ,or a loose one, which you could check with an AM radio

 

[audioguru]

The same problem (wire came loose from the battery?) that blew-up the CD player's amp probably also shorted its supply filtering circuit. So now instead of having a filtered supply, the CD preamp is connected directly to the alternator. The player's CD laser and guidance circuit probably won't last long that way.
An "audio equipment supply filter" (choke and capacitor) can be obtained from a car radio shop. It should stop the alternator whine until the rest of the player blows-up.

 

[zevon8]

You may also have a "gound-loop" picking up noise in the connection between the amp the CD player. There are simple adapters you can get from most car audio places or any where that sells car audio equipment. they plug into the line between the amp and the player, isolating the grounds. Even Radio Shack sells one. Some better ones are 1 to 1 transformers, others are simply a capacitors and a resistors.

 

[stevez]

A failed diode in the alternator can be the problem - had that experience already. Amplitude is just too much to filter - and if it's failed diode the charging system is impaired anyway so best to fix that problem first.

 

[Electric Rain]

Well, I don't know much about the matter, but I can say this: Try powering it from a different 12V source. If there's no whine, then you know what the problem is.

Rain

 

[jrz126]

A failed diode in the alternator can be the problem - had that experience already. Amplitude is just too much to filter - and if it's failed diode the charging system is impaired anyway so best to fix that problem first.

just took it to advance auto, they have a tester that just hooks up to the car. It said the diodes are good, volt output is 14V and it's only putting out 65 amps. I dunno if the kid did it right though, he almost reversed the connectors to the battery good thing I was there to let him know which on was positive :roll:

Will an alternators output decrease slowly or will it just quit working?

 

[audioguru]

Yeah, you must watch those mechanic guys (called technicians now).
I saw one use a power wrench on the decorative bolts of my wheel covers!
I hope that yours didn't overload your alternator when he tested it.

I took my car in to have its 5 years old coolant replaced. They don't just do that, you must order their "cooling system maintainance package".
For the pressure test that I didn't even need, they used such a high pressure that they nearly blew the engine apart. They presented me with a $1200CAN estimate to re and re the engine and replace its leaking water pump! In 5 years it didn't leak a single drop! They didn't even replace the coolant because they said it will need to be done again anyway when the pump is replaced.
I had to replace the coolant myself (what a mess) and luckily the pump also didn't leak after their "test".
At a different dealer, my transmission computer error code is a similar story. I got rid of that car and those dealers.