Volkswagen Mark IV Forum banner
1 - 19 of 19 Posts

·
Registered
Joined
·
108 Posts
Discussion Starter · #1 ·
I know this must get asked time and time again, I've have been trawling through the net and would like some help.

I have a JVC headunit, and the reception has never been great, but has gradually got worse. If driving along, on FM it will come and go. I can barely get local radio, and most cloudy days it might as well be switched off! I've fitted a brand new genuine base and a PC5-90 signal booster, however the old base, other than a little corrosion looked fine! I have swapped a megane aerial and no better. It's really frustratig now, is there anything I can try next? I dont want to buy a new stereo for it to be the same. Are there any faults with the aerial cable?!

I foud these mods on a forum, are they any good? Do they work? there's one on page one and one on page 2.

http://forums.tdiclub.com/showthread.php?t=240678

Any help appreciated!
 

·
Adrian
Joined
·
4,149 Posts
the PC5-90 jobby wotsit isnt a signal booster, its a phantom power supply for the areal base. it needs a switched 12v feed connected to the blue lead (remote amplifier on from the head unit will do).

If you've done that ad still getting poor reception, then i can only guess the antenna wire has broken/shorted out somewhere between the base and the head unit.
 

·
Registered
Joined
·
108 Posts
Discussion Starter · #4 ·
Yeh, it's wired in on the remote 12v feed. I really dont fancy dropping the entire roof lining to change the aerial, plus it has VW connectors on one end.

Running out of other possible ideas [:(]
 

·
Super Moderator
Joined
·
50,234 Posts
If you stick any random length of wire or even small screwdriver into the aerial socket,do you now get radio reception?

Chris.
 

·
Registered
Joined
·
108 Posts
Discussion Starter · #7 ·
Firstly, I have asked about to see if anyone has a spare HU that I could try. Ironically I was looking to buy a bluetooth alpine one that would work with my iphone.

Secondly, I tried sticking a screwdriver in and its about the same. Hard to see any difference, I can get Radio 1, okish but thats it.

Obviously the original cable has fitted connectors at each end, do VW sell just the cable? I need to buy a multimeter really to check that the PC5-90 is working correctly. Does anyone know what the restiance should be on the VW aerial cable?

Thanks for your advice!

Chris
 

·
Registered
Joined
·
108 Posts
Discussion Starter · #9 ·
FYI, changing the antenna base takes 10 minutes, you only need to drop the bracket inside the boot hatch, and you can reach in and do everything easily.

And using a power booster, my mk5 antenna works fine.
Changed the base for a brand new one, like you said took 10-15mins and a 22mm spanner. But its made no difference, already had the "signal booster" fitted.
 

·
Super Moderator
Joined
·
50,234 Posts
If you've plugged a screwdriver into it (you needed to touch the metal part of it ) and it was no better,then it's a faulty radio.

You can't just put a multimeter on the PC5-90 as you won't get a reading that can be used to tell if it's working or not,but as before IT'S NOT A BOOSTER AS IT DOESN'T BOOST OR AMPLIFY THE SIGNAL IN ANY WAY .It is a phantom power supply that sends power up the aerial co-ax cable to power the matching amplifier built into the base of the aerial.Again this is NOT A BOOSTER AMPLIFIER but it makes the radio "think" the aerial is a lot longer,but just for MW and LW reception and has next to no effect on FM reception as the aerial is already the correct length for optimum FM reception.

It's important you understand all the above bold type before you waste any more time and money buying parts that you don't need.

Chris.
 

·
Registered
Joined
·
108 Posts
Discussion Starter · #11 ·
I understand perfectly... I know what it does, but putting "phantom power supplier" seemed odd. I know it supplies a 12v feed to the the amplfier in the base!

I'm on the hunt for a HU to borrow. I put a phillips screwdriver into the centre hole and it was on par, "maybe" a little better, but not that it was clearly noticeable. I could get Radio 1, but not radio 2.

I purchased a replacement multimeter, as I think my old one is back in St Albans. This is where I need clarity, the "phantom power supplier" sends a 12v feed along to the aerial base. Surely I can check the integrity of the cable by disconnecting the base connector and checking there's a 12v feed there?! I touched the probe to earth and the outer terminal inside the connector and it only read 1.4v. This can be right can it?

Chris, I do appreciate your help, and aplogies for my ignorance!

Thanks,

Chris
 

·
Super Moderator
Joined
·
50,234 Posts
A "phantom power supply" just means one that doesn't have a seperate power supply wire.Masthead TV amplifiers work this way as do most condensor microphones that need an amp at the mic end,so they get their power via a "phantom" wire that doesn't really exist.

Forget about the PC5-90 for now,it's only making matters a lot more complicated than they need to be and if you only ever listen to FM and not MW/LW then you don't need it anyway.Take it out,put it into a sturdy box,wrap it up with parcel tape and send it to somewhere a long way away so you're not tempted to waste time with it again[:p].It's not your problem and never has been,as above your JVC almost certainly has a faulty tuner module in it.The strong local FM stations coming and going is furtther proof of this.

Chris.
 

·
Registered
Joined
·
108 Posts
Discussion Starter · #13 ·
Right, my brother and his girlfriend popped in this evening, and I borrowed her Kenwood HU. She has a polo,cand her reception is spot on, I plugged it into mine without the PC5-90 and it was crap... didnt even pick up radio 1.

Now is this looking more like the cable?

I've tried:

New aerial base, HU, with and without PC5-90, New aerial mast...

I'm completely out of ideas.

Chris
 

·
Super Moderator
Joined
·
50,234 Posts
Before you go the trouble of running a new aerial cable,try just one last time something like a 1 metre length of wire plugged into the aerial socket.If it doesn't pick anything up on this,then the radio is definately goosed.
Probably too late now,but what happens if you try the JVC in the Polo?

Chris.
 

·
Registered
Joined
·
108 Posts
Discussion Starter · #15 ·
too late to try the other way round, they were only here for 10mins, and after the Kenwood was the same I gave up. Just out of curiosity, do VW sell the cable?

I have some household co-ax cable, so will run that and see. back in 5...
 

·
Registered
Joined
·
108 Posts
Discussion Starter · #16 ·
ok, basically cut the co-ax to expose a length of wire, and isulated the outside with a latex glove. Plugged it in and the reception was much better, could scroll through a pick up channels etc. Still crackly at times whilst driving along, but alot better. Plugged the car's aerial in along the drive and it was still poor. So I was thinking aerial, then I got back and plugged the car's aerial in and pushed the stereo back in it's cage and the reception was as good as the length of ao-ax... This is playing games with my head. I'm wondering if there's damage to the aerial cable behind the dash.

I'll see how it goes this week, it'll probably be rubbish again as soon as i drive to work. Are the cables easily sourced?
 

·
Super Moderator
Joined
·
50,234 Posts
VW do sell the cable,but it would probably cost more than the gross national debt of some third world countries[:O].You can buy universal aerial extensions from 0.5 up to 5 metres for not very much money,domestic cable normally not suitable as it's single stranded so not very flexible.

Chris.
 

·
Registered
Joined
·
108 Posts
Discussion Starter · #18 ·
I did see those on ebay, thanks for the heads up. What do you do with regards the VW aerial base connector? Foud the right angled ISO connector for a £2.50 on ebay.
 

·
Registered
Joined
·
108 Posts
Discussion Starter · #19 ·
Drove to work this morning and the reception was amazing...!!!! Best its ever been in the car! I'm going to put it down to a bad ISO connector on the aerial cable behind the HU. The fault has to be located there as it went from poor to good just by pushing the HU back in.

I appreciate all the help and advice, atleast I'll know how to fault find in the future! Will buy a new connector off ebay and give it a go when I change the HU in a couple of weeks.

Chris
 
1 - 19 of 19 Posts
Top