what is wrong?

[harrytherid]

My Philips car stereo cem3000b works fine in my Fiat Ducato based Motorhome in all respects until the ignition switched on then terrible interference ensues. I have made up a cable to ground the stereo chassis directly to the battery negative to no effect. One thing I did notice was that when my dash cam comes on the situation worsens so I unplugged the dashcam and there was an improvement but still very poor reception. What am I doing wrong?

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[Jimi77 5,000+ posts]

Is the interference there when the ignition is on, but engine isn't running??

 

[harrytherid]

Thanks Jimi, I will check that but I don't think so or not so bad, I think, sorry but old so poor memory, so I will need to go out and check, I will confirm later.

 

[harrytherid]

Bad with ignition on, maybe a little worse with engine going, but my ears are not so good any more. When I can I will get my wife out there to have a listen. She has the ears of a bat and will detect any differences

 

[1aespinoza 10+ year member]

What am I doing wrong?

Is the radio connected to an amplifier, ipod, or any other electronic device?

 

[harrytherid]

No "1aespinozaIs" the radio is not connected to an amplifier, ipod, or any other electronic device? it has a USB socket on the front so I can plug in a memory stick. When I did so briefly, it (the memory stick) was fine but I unplugged it before turning on the radio

 

[1aespinoza 10+ year member]

No "1aespinozaIs" the radio is not connected to an amplifier, ipod, or any other electronic device? it has a USB socket on the front so I can plug in a memory stick. When I did so briefly, it (the memory stick) was fine but I unplugged it before turning on the radio

So it is the radio direct to the speakers and the only peripheral is the reverse camera. The issue is with key ready to crank but engine off. When you say interference, do you mean radio stations or on all formats?

 

[hispls 5,000+ posts]

Some radios/amplifiers will make horrible noise if a speaker wire is shorted to ground. It might be you have a speaker wire touching some metal in the vehicle. This may be very difficult to detect if some stock wire is failing under a carpet or in a door conduit or similar.

How do your speakers connect to the source unit? Some factory wiring or wiring you installed?

 

[harrytherid]

Right I have a definitive answer. Ignition off perfect, ignition on interference. Madam bat ears says there is no difference between ignition on (bad interference) and engine going (equally bad interference). Pretty sure there are no dodgy speaker wires which are original factory wiring, and it is only the radio that is affected. Recorded music perfect. I have tried grounding the radio chassis direct to the battery negative with connections both crimped and soldered to no effect. the radio is not directly connected to any other devices. And whatever the result, thanks for helping, everybody.

 

[dragon.breath 10+ year member]

The antenna or antenna wire could be bad. I had a car several years ago that the plastic antenna mount was bad and allowed the antenna to ground on the car fender. The mount looked normal while mounted to the car. I figured it out by disconnecting the cable from the head unit. No radio stations, but also no noise.

 

[harrytherid]

Antenna unplugged, noise reduced markedly but not gone. Plugged in again and ignition switched off, noise gone completely so antenna not the only problem but maybe a better one might help. Any advice there would be appreciated but money short (living on state pension) so no expensive fixes.