Car radio wiring

kobuskint · 19-04-2005, 08:09

I have used a car cd/radio and spare (non-car) speakers to supply decent sound to a garage and to outside speakers. I used a car radio because I had a spare one and to get four speakers all going at a decent rate (4x50W). The power supply is a 10A 12V unit that I refurbished.

The sound is great from the CD but I cannot get any radio reception.

I cannot guarentee that my radio has not got a tuner problem, but using a new car radio antenna and a single core wire, I can get hiss, but no reception of any kind on either FM, MW or LW. If it was mute I would say the tuner was broken, but I get hiss and if I take the antenna out, this hiss stops.

I have considered poor earthing but do not know how to check or earth the head unit.

I have the switched and permenant live wired together (red and yellow), and there is a neutral (black) to the power supply. Apart from eight speaker wires there are two blue amp wires (not used and isolated) and a single blue wire (not sure what this is) that is isolated and not connected to anything.

Has anyone any thoughts or ideas, before I buy another stereo? It seems a shame because the systems works well apart from no radio signal.

Thanks for your help.

KK

Roy MM · 19-04-2005, 08:35

Are you in a metal covered garage? no reception, the unused blue wire will be for a motorised antenna.

paulyoung666 · 19-04-2005, 08:39

guess time , if you connect the aerial to the metal of the cd player what happens , when i say connect i mean the part of the aerial that would normally be in contact with the car body , if you see what i mean

kobuskint · 19-04-2005, 08:41

I have no problem with radio reception normally in this room.

Thanks for the blue wire information. Therefore, I am ok to isolate it and not worry about it then? I guess that it will have no impact on the reception (I am not sure what a motorised antenna is).

KK

Roy MM · 19-04-2005, 08:46

Motorised, it pops up the antenna when the radio is turned on.

kobuskint · 19-04-2005, 09:00

Oh yes, motorised antenna. Doh!

At the moment I have a car antenna, with a male jack. There seems to be two parts to the jack ie. positive and negative, certainly isolated from each other. The single core trailing aerial wire is screwed into the male proboscis that fits into the head unit. The outer part of the jack is not connected to the wire at all and I presume the antenna is connected to the case of the head unit by the isolated part of the antenna??

This is my jack:

http://www.maplin.co.uk/Module.aspx?...ldID=&doy=19m4

How would I connect it to the head unit case?

paulyoung666 · 19-04-2005, 09:08

Quote:

Originally Posted by kobuskint

How would I connect it to the head unit case?

just get a bit of wire and touch the aerial base to the case of the cd player

kobuskint · 19-04-2005, 09:13

Quote:

Originally Posted by paulyoung666

just get a bit of wire and touch the aerial base to the case of the cd player

Sorry Paul, but on the antenna jack, is that the metal connected to the aerial or the metal not connected. Perhaps I just need to try both. Will this just ground the antenna?

ian@huth · 19-04-2005, 09:28

Quote:

Originally Posted by kobuskint

Oh yes, motorised antenna. Doh!

At the moment I have a car antenna, with a male jack. There seems to be two parts to the jack ie. positive and negative, certainly isolated from each other. The single core trailing aerial wire is screwed into the male proboscis that fits into the head unit. The outer part of the jack is not connected to the wire at all and I presume the antenna is connected to the case of the head unit by the isolated part of the antenna??

This is my jack:

http://www.maplin.co.uk/Module.aspx?...ldID=&doy=19m4

How would I connect it to the head unit case?

I like the top aerial listed on that Maplin page.

It sounds like an earthing problem with the radio. Take a thick wire from the radio chassis to the neutral on the power supply to see if that helps.

Alternatively it could be a problem with the radio itself. A defective capacitor may be cutting off the DC voltage to the receiver module or radio muting when a CD is played may be staying on when in radio mode.

I don't think it is anything to do with the aerial not being connected to the radio case but it could be a faulty aerial. Only real way is to try the radio in the car again if this is convenient.

kobuskint · 19-04-2005, 09:38

Cheers Ian. Just to make sure, that would be the black wire going into the 10A power supply? If I secure a wire onto the chassis of the radio to the negative power supply, this might ground the unit?

I will let you know tomorrow how I get on. It really feels like a grounding problem, but I just did not know how to fix it.

Thanks for everyone's help.

kobuskint · 19-04-2005, 18:32

I have tried the radio in the car and it is fine. I have also tried connecting a thich wire to the neutral (black) power lead fro mteh power source. I still get lots of hiss, but no radio. Any other ideas?

Cheers

KK