Becker GP Installation. Help!!

bodmin · 14 May 2015

After several months I finally got around to attempting to fit the obligatory Becker GP to my 993. Becker bought from Tore Bergville, and a very fine unit it looks too.

I pulled out the existing Kenwood, only to find a birdnest of cables, DIN plugs, ISO plugs, and various unrecognisable plugs. My conclusion is that despite only 44k miles my 993 has had at least 3 previous radio units installed (I have two of them). There is also a 6CD unit in the boot which I no longer require, but was part of the cabling.

To cut a long story short I plugged the ISO live, switched live, and ground plug into the Becker and fired it up with a CD. All lights on and CD reading but obviously no sound.

I plugged in the yellow plug into the C socket on the Becker - still no sound. Had a look at the amplifier end under the seat and found that the other end of the DIN plug was unplugged. I plugged it in - still no sound. Checked the amplifier fuse - ok. The yellow plug, grey cable, and round DIN plug at the amp are all part of the original loom.

So at the moment I'm trying to figure what's wrong. Can't see anything in the Becker instruction indicating that the C socket output can be switched on/off.

Only positive thing so far is that I found a spliff under the seat!!

I have two other questions about the wiring:

1. Can anyone tell me what the thin black wire which comes out of the aerial lead is for?

2. Can anyone tell me what the thin green wire which comes out of the original loom is for?

Any help gratefully received. Apologies for the rubbish pictures. In the meantime I'll go and check out that spliff.

dommorton · 14 May 2015

The thin cable on the aerial is the switched power lead for the aerial amp which is situated on the bulkhead behind the dash. It's visible if you pull the clock out.

The rest looks a bit of a pickle. Certainly seen some upgrading over the years.

I hope you work it out.

bodmin · 14 May 2015

dommorton said:
The thin cable on the aerial is the switched power lead for the aerial amp which is situated on the bulkhead behind the dash. It's visible if you pull the clock out.

The rest looks a bit of a pickle. Certainly seen some upgrading over the years.

I hope you work it out.

Hi Dom,

That's a useful piece of info.

I just need to cut out all the unecessary wires and get back to the basic live, switched live, and ground. Just can't figure out yet why there is no sound when the yellow plug which connects directly to the amp does not result in sound.

I'm sure I'm missing something simple.

bodmin · 14 May 2015

I'm thinking that the amp under the seat needs a power supply from the head unit.

Can anyone confirm or otherwise? The wiring diagram in the Bentley manual is far from clear.

Pickled Piper · 15 May 2015

You have the proverbial "plateful of spaghetti" behind your dash.

I can see speaker leads with phono plugs amongst the spaghetti. It looks like the previous owner may have bypassed the amp and connected the head unit straight to the speakers.

Sorry I can't be more helpful. I am assuming the original amp did not work previously?

pp

bodmin · 15 May 2015

I've now removed all the extraneous wiring, there is now a simple socket which plugs into the Becker with live, switched live, and ground.

The thin black wire is for the aerial amp which I'll worry about later. The thin green wire is for the burglar alarm and connects to the radio case, again I'll worry about that later.

I can't understand why the original cable which connects to the Becker C1 socket at one end, and the amp DIN plug at the other end is not delivering the goods. The cable is original, untampered, and I have checked each core for continuity.

The amp has its own power supply and grounding, and I have checked both with the meter. All ok. The amp was working with the previous Kenwood radio using the DIN socket input.

I will persevere for a while longer before giving up and going to a local radio specialist. However on the face of it I think it should work, and I am missing something fundamental.

Pickled Piper · 15 May 2015

I can only suggest emailing Tore Bergville.

He was very helpful when it came to installing mine.

993tt · 15 May 2015

When I took out my CDR21 and fitted a Becker cascade I only had a few cables to swap over but I was very disappointed that it all looked good but no sound. It was a long time ago but I seem to think I ended up taking the C6 line and connecting it to A5, I can not remember what the reasoning was or what the designations of the lines were but it has worked ever since. Sorry to be so vague

ToreB · 15 May 2015

Thanks for the references all, I have been in touch with the thread starter by email.
The Becker GP has the +12V antenna/remote on output on pin A5. C6 is the subwoofer line output. I would not recommend to interconnect these. These pins may be different on the Cascade.
Cheers,
Tore

Fourtuitous · 15 May 2015

Hi Bodmin, A few of us on the 993 forum with S cars with the Nokia Amp have had this problem. There is an anomaly in the 993S DIN cable pin allocations that does not conform with the standard normally used. The Nokia Amp requires a trigger input on the centre pin (pin 6). This trigger needs to come from socket A pin 5 on the Becker unit. As Tore says this is the control output for the automatic antenna / amplifier. Without the trigger voltage the amp won't work. Unfortunately the 993 cable has its trigger wire (which is white in the cable) connected to pin C6 at the other end for some reason which is the sub woofer LineOut. So you need to shift the white wire from C6 to A5. This is why many have been butchered by inexperienced fitters who could not get the amps to trigger. I have attached a diagram I drew to keep myself sane while I was going through the same process you are going through. I was given this advice both by Becker in Germany and by a renowned Becker expert in the UK. It worked for me and it has worked for several others on here too. Good luck in getting it sorted.

ToreB · 16 May 2015

Highly appreciated! A pinout diagram available on Rennlist states that Nokia amp pin 8 is unused. Picture saved for future reference.
Cheers,
Tore

dommorton · 16 May 2015

Weird that. My MY98 4S had a CDR-21 in it per factory when I got it. This with the hi-fi package and Nokia Amp. I just popped my Becker GP in and off she went. None of this carry on with the DIN plugs :dont know:

jonttt · 16 May 2015

Some more info and pics on my journal.....

http://911uk.com/viewtopic.php?t=82158&postdays=0&postorder=asc&start=109

Rialas · 16 May 2015

dommorton said:
Weird that. My MY98 4S had a CDR-21 in it per factory when I got it. This with the hi-fi package and Nokia Amp. I just popped my Becker GP in and off she went. None of this carry on with the DIN plugs :dont know:

This exactly the same for me. I've switch back and forth (unable to decide which I like the look of), from my original cdr21 to the Indianapolis, and never a problem for the nokia amp to recognise either.

bodmin · 17 May 2015

It works, it works!!!!!

Firstly apologies for no replies over the last 48 hours. I was off to the West Coast of Scotland staying with friends in Port Appin where t'internet is not the best. Great hospitality, and large quantities of Glenfiddich consumed.

One of the high points was seeing a black 993 C4 parked at a house near Ballachulish. I was going to stop and find the owner, but Mrs B and kids objected as they just wanted to get to the end of a long drive in Mrs B's X5. Unfortunately the 993 was gone when I looked for it on the return journey. If the owner is on this forum please get in touch.

Anyway back to the Becker GP. Mr Fourtuitous and 993tt - thank you so much for your replies. As soon as I got back to Edinburgh I was straight into the man cave, removed pin 6 from the C1 plug (used a couple of safety pins to release the pin). I then used a short jumper to connect this pin to plug A1 terminal 5.

I powered up the radio and was soon listening to the Thomson Twins on CD (yes I know, but it was the only CD I could find in a hurry!)

Thank you to all on the forum for all the help, and again to Tore who had independently suspected a wiring issue within the C1 plug. I'm absolutely delighted to have had this problem solved!

I'm off to Stuttgart tomorrow for a factory visit with another Edinburgh Porsche enthusiast, and then off to work in Baku for a couple of weeks. When I get back I will have all the hardware and cloth tape to complete a neat radio installation in the 993.

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