INOP Radio

[csjcarolyn]

I recently bought a new Philips CEM 3000B DAB/FM radio which will not work properly.

Often it lights up with a station number but will not play.

Sometimes it starts but if I switch off it will not play again.

Quite by accident I noticed if I ease the plug out of the radio the speaker leads arc then it plays until I switch off then will not start again.

Obviously I have taken it back to the supplier twice and it works fine. A logical conclusion is the installation in my car. I therefore pinched a speaker out of my wife's car [she hasn't noticed yet!] and plugged it STRAIGHT in the back of the radio - it stiil will not work.

I feel it must be an internal radio problem, something to do with the arcing and resuilting spike? I will be going back to the supplier again but wonder if anyone else has had this problem.

Hope this keeps your little grey cells happy.

[stevejgreen]

Re: INOP Radio

Interesting, and difficult to diagnose remotely.
It sounds as though perhaps the radio is trying to ground its way through the speakers. A little unusual as speakers themselves should have both terminals insulated from ground.
Have you tried running new power leads + and - to the fuse conection and radio chassis and using the existing speakers?
Are you relying on the antenna for an ground? The antenna needs a ground connection and preferably a 'ground plane' or part of the body metalwork. On most cars the body is steel or aluminium but on kit cars it might need a metal mesh underneath the antenna.

[Dane_Rescueman]

Re: INOP Radio

Roger, is your car negative earth ? Older systems were positive earth. The antenna earth would give a live input in this case.
If the speakers are in the doors as mine are, it is possible for fatigue to affect the insulation and core in the flexible cable twixt door and car.
The CEM has a code. Have you a constant feed to the KAP pin on the radio? If not this could cause the strange operation each time you switch on. Sometimes this connection and the main power feed get reversed during installation. which can cause strange FX.
It is not unusual to get a little spark if you unplug the speakers whilst the radio is operating. On most high output amps there is a hefty output capacitor which can be discharged as plug pins move out of connection. I had an ancient Marshall amp with glowing milk bottles (valves)for drivers. This had a beer tin sized output capacitor across the output which sometimes arced when reconnecting.
Is there a feed from the instrument lights? Modern radios have their own internal lighting but some have an input from the instrument lighting circuit in order to give a dim signal to the radio lighting. Unlikely this one!
Has any cable been attached to the bluetooth or ohone pin? This mutes the radio if set up in a car hands free system. This should remain unconnected in a vehicle without hands free.
Otherwise, sadly, recheck each cable run and the wiring of the radio connector. Look for any shorts by wiggling the cables whilst checking them with a meter.
The final but tedious test would be to get the supplier to test the radio in your car.
Of note, here in the Cornish boonies, my various radios tune in to DAB stations but will not play at all due to a snag with signal strength I suppose. The DVB radio stations work OK though as does FM.
Goos luck with it!

[fredsajs]

Re: INOP Radio

HI Roger,
Word of warning re speakers and earth.
My antenna is mounted on aluminium side panel of car and found that fitting a new replacement antenna, now needed a seperate earth to base of antenna not as is was on old antenna together with a coax cable sheith earthed also.
I found that if co-ax on antenna was not earthed then it uses case of radio to find earth. If case is not earthed it uses speakers case fixing, to get its earth.
If radio is not + earth and your car battery is, then the full amp of battery will travel to an radio earth point I have previously stated ( or visa versa if -ve earth).
Regards
Fred

[silver-back]

Re: INOP Radio

check alternator output too as if overcharging?

[csjcarolyn]

Re: INOP Radio

Thanks for all your comments. Regarding Steve's comments. My previous radio speakers were grounded but this radio has two speaker leads per speaker and earths through the radio and I had run in a new power lead from the ignition key, both that and the permanent power lead had high battery voltages available. I tried a new aerial and wired that directly to the battery earth terminal.

Regarding Dane's, Fred's and Gteg's comments. My speakers are in a static panel in the boot panel so not subject to too much vibration. I don't know where my mobile is let alone bluetooth! Everything else seems ok and the alternator works well, over 13V with headlights on.

And now for the solution! I cheked speaker lead continuity right through to the earth connection. This was 0.1 Ohms - so ok. I checked the earth route back to the battery - again 0.1 Ohms. When the radio did work I checked the voltage available at the end of the input speaker lead, this was 6.5V so ok, yes I did wriggle the leads - very agressively! In desperation I rewired the speaker leads, despite the above readings and it worked and has continued to do so ever since!

I think electricity was invented to punish me for my sins!

Thanks again for your words of help.

Roger