Radio aerial amplifier

[geoffbateman]

Does anyone know where this is located at all. According to the electrical diagrams there is a powered aerial amplifier fitted to my 944 Lux 1987 which uses an embedded aerial in the front windscreen. I've been trying to find it for the last couple of days and am a little reluctant to dismantle any more of the dash without a little idea of where I'm going. The workshop manual seems decidedly sketchy on it and gives no details of where to find it, but it is shown on the circuit diagrams. Any suggestions gratefully received.

 

[pauljmcnulty]

It's under the bonnet, NS corner of the windscreen. There should be wires coming from the screen where the ariel starts/ends.

 

[chrisg]

Paul is spot on, if you follow the wire from the drivers side of the bottom of the windscreen you'll see the wire, on my car ('88 turbo) this wire goes through a grommet in the bulkhead. I seem to remember that the amplifer is a black rectangular box somewhere underneath the steering wheel up near the dim-dip control unit.

 

[jmelhuish]

Ahhh. This grommet could be where the rain water is making its way in to the drivers side foot well of my car . Thanks for the inspiration

 

[geoffbateman]

Thanks for the replies. I'll renew my efforts around that area. I can see where the embedded wires are in the screen on th RH side but I started trying to trace the cable back from the radio end and I've got 1/2 the dash out now and still no further on. The original radio was replaced by a former owner who had a new sony unit fitted by Halfords. The CD all works and I can see where they've mated the harnesses and it's all been crimped and I'm quite happy with that, but the radio has never worked. My guess is it's either a faulty amplifier, broken connection, or my next thing to try which is to check power to the power feed to the amp. This is a black wire attached to the aerial co-ax and I've just started wondering if the Halfords expert has connected this to ground instead of antenna feed?

 

[steves944]

I get terrible reception on my radio, is that somewhere to look to see if its stopped working?

 

[geoffbateman]

Thanks Paul I have found it exactly where you said it would be. There ia a supply connected from the radio which comes on when the radio is switched on but I get no reception whatsoever. All the connections look OK as far as I can see so I'm guessing the unit is U/S. Are these a problem at all, is failure a regualar thing? Is it worth replacing? Any comments gratefully received.

 

[Pastry]

my reception was crap when i fitted a new sony unit, had to hook up a supply to the aerial but cant remember exactly how, think it was a blue wire from the stereo to a black wire in the dash wound with the aerial coax lead, but couldnt guarantee it.

 

[bmnelsc]

There is a pretty good article about 944 stereo wiring here - http://www.connactivity.com/~kgross/FAQ/944faqst.html

I also had a Sony in my 1991 S2 when I got it - no reception. When I pulled the stereo to check the wiring I found the stereo didn't tune to the FM bands required (Car came from Japan to Canada) so the fix was easy for me - put in a new stereo.

I was able to determine that the stereo plug was correctly wired including power to the antenna amplifier using this article (and confirmed with the Porsche wiring diagrams). I was lucky - the late style Sony plug was added into the stock harness which also included the standard Blaupunkt plug and the wiring for the telephone system. This all appeared to be standard wiring in 1991 regardless of options actually installed. So - taking the easy way out - I popped in a new Sony - just had to exchange the mounting sleeve from the old stereo for the new one. Radio reception is pretty good now.

Sorry didn't speak to the question - the antenna amplifier power is the black wire "twinned" with the antenna coax and yes it needs to connect to the "power antenna" lead off the back of the Sony wiring plug. IIRC it is a BLUE wire out of the Sony harness. This lead only supplies power when the radio is on. I don't know if power is supplied only when AM/FM modes are selected and off when CD/USB/IPOD/Sat etc. modes are used but the important part is power is only supplied when the radio is on so it won't drain the battery by powering the antenna amp even when the car is off (this can happen if you connect the 12V constant supply to the antenna amp).

 

[944Turbo]

When i bought my cab the sony minidisc head unit radio was faulty, popped in a new one and that fixed it! but yes from memory I think stereo power antenna cable is blue and the in car one is black run with the antenna cable.
Tony