Hi,

I've just bought a really nice Croma which has the satellite navigation option which works beautifully.

I get great FM reception and pretty good LW reception but the MW reception is almost non-existant. I can tune the station in, but there is a lot of background noise.

All my previous cars bar an 2002 Vectra had great MW reception at the same location (my home).

Now, Vauxhalls have rubbish MW reception because an aerial amplifier breaks. The Croma is loosely based on the Vectra C I believe, does the Croma have the same system?

If it possible to fix it myself I will, although I am prepared to take it to an audio place to see what's wrong with it.

Stewart

I didn't know anyone still listened to MW. A cricket fan?

The standard (non sat nav) stereo is Blaupunkt, designed for Fiat. I don't think it shares any heritage with GM. I'd guess the sat nav is the same - does it have a Blaupunkt badge?

LW is for the cricket, yes a big cricket fan. MW is for the football - 5Live and TalkSport. Euro2012 at the moment!

I will have to take the double din system out and have a look to see if it is a Blaupunkt. I guess using an aerial booster is a no go - it's the background noise that is the problem not picking up the station.

Once in an old BMW, the radio has FM, MW, LW and SW!! (it wasn't an old police car!) No idea what you would use short wave for...?

stranter said:

Once in an old BMW, the radio has FM, MW, LW and SW!! (it wasn't an old police car!) No idea what you would use short wave for...?

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Listening out for the message "calling all cars, follow that beemer doing 120mph"

Check the aerial threads are free of corrosion . Cost me £20 to be told this by a tech.

Aah, will do!

FWIW, I was looking at short wave car radios and Blaupunkt seem to be somewhat of a specialist. Local German radio used to be (maybe some still is?) broadcast onit.

What aerial threads, the radio antena is incorporated into the rear glass and the gps fin on the roof is gps only.

MW interference is usually caused by either a poor aerial earth (back radio connector or aerial mount to car frame) or negative feedback. You can buy supressors to help stop it.

notorious said:

What aerial threads, the radio antena is incorporated into the rear glass and the gps fin on the roof is gps only.

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I don't have a fitted sat nav, and have a rubbery spike aerial sticking out of the roof above the back window. Is the aerial in the window when GPS is fitted?

I would have thought the rear aerial is FM only though. Is there an AM aerial elsewhere? Or is that's what's in the rear window?

I'll have a look on eLearn next time the proper computer's on.

Sorry wrong car I had a momentary lapse...

Doofer said:

I don't have a fitted sat nav, and have a rubbery spike aerial sticking out of the roof above the back window. Is the aerial in the window when GPS is fitted?

I would have thought the rear aerial is FM only though. Is there an AM aerial elsewhere? Or is that's what's in the rear window?

I'll have a look on eLearn next time the proper computer's on.

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The aerial is for all the waves, if you take it off by unscrewing then you can still get some FM reception from local stations but virtually nowt on MW. forgot to replace it after several car washes, but now leave it on and only use ARC whose top brushes rotate the right way so just flatten it towards the back of the car instead of picking it up and forcing it towards the front of the car against the slope.

tarquin1867 said:

Check the aerial threads are free of corrosion . Cost me £20 to be told this by a tech.

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Unscrewed the aerial today. The brass coloured thread on the aerial was corroded as was the part on the car, so I cleaned both and it has massively improved the reception.


I am going to take it off tomorrow and clean the threads further. Any suggestions with what? I used wire wool and a wire brush today but with no assisting cream or stuff. I was thinking petrol or metal cleaner or white spirit. Good idea? Would it be worth putting a spot of grease when I screw it back together too?

Stewart

I'd use something with a fine abrasive, e.g. duraglit metal polish or even bathroom cream cleaner. Just screw/unscrew it into a cloth for the male, perhaps try cotton buds for the female or just a corner of the cloth. Just make sure it's all rinsed off by wiping with white spirit. I'm pretty sure it's solid brass, so hopefully there's no plating to worry about wearing off. Just be careful not to grind too much of the screw thread away.

Standard grease and lithium grease (the white aerosol stuff) are not conductive, so probably not a good idea. I don't know whether the metal-metal contact would still allow good contact even with an insulating grease. I know copper grease is commonly used on battery terminals, but I don't think it's rated as a conductor, and the aerial power is far, far lower so would be more affected by an insulator in the way. You can get silver grease, but I'm not sure if this stays greasy or sets - it's often used on heatsinks in electronics where it hardens, but it does see a lot of heat in this situation. I'm not sure what's best. I suppose you could test a grease using a blob of it and a resistance meter. Mine's bone-dry and it works fine. Perhaps yours was left loose for a while and the rain got in.

It's always good to hear of a problem solved that doesn't involve dismantling the entire car into its component parts though.

I have seen graphite grease accidentally conduct (actually ignited), but may need a considerable current.

stranter said:

Unscrewed the aerial today. The brass coloured thread on the aerial was corroded as was the part on the car, so I cleaned both and it has massively improved the reception.


I am going to take it off tomorrow and clean the threads further. Any suggestions with what? I used wire wool and a wire brush today but with no assisting cream or stuff. I was thinking petrol or metal cleaner or white spirit. Good idea? Would it be worth putting a spot of grease when I screw it back together too?

Stewart

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I have used wire wool to clean off the corrosion and paper towel to clean both parts afterwards. As it is water that leads to corrosion I have smeared clear silicone sealant on the rubber face of the aerial and repeat this when i have to take the aerial off for any reason . Have had no corrosion/ reception problems since

Right, well I have used some metal cleaner and it is better, but still not right. I will take it to an audio shop near me an see what they say. Maybe just needs a new aerial?

Nah - just give it some pasty with the polish. They'd only flog you a new aerial that's not as good as your original.

Toothpaste might work well, especially if it's for smokers.

Well, I have finally fixed this. I know what was causing it. A duff alternator either not providing enough power or causing some form of electrical interference.

Battery light came on, alternator was replaced and all is well with the radio reception now!

stranter said:

Well, I have finally fixed this. I know what was causing it. A duff alternator either not providing enough power or causing some form of electrical interference.

Battery light came on, alternator was replaced and all is well with the radio reception now!

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What!---- the alternator packed up on a Croma!! now that is very rare LOL

I know, a problem with a Croma's alternator?

(You know I am sorting the EGR too? These Cromas are pretty predictable!)