max3.2

Hi,

I'm in the process of fixing my radio (on a '91 964 conv.) and while doing so installing a new HU. I'm sticking to Alpine (126 to 192 HU) since someone wrecked the wiring and its kinda a mess back there. The current main issue is a very bad radio reception and some current drain. I did some diagnosis and maybe you can conform some issues so I can fix them.

1) Bad reception: There's a white wire from the car connector thats not connected. From the wiring scheme thats "antenna amplifier" - the headunits have something similar which presumably supplies +12V as soon as the radio is on. Am I thinking right that my Antenna needs its amplifier power which was disc. all the time and thus the reception was bad. My fix: connect this white wire to the switched +12V on the radio..?

2) There's a yellow wire in the cars connector which isnt connected. Also, it isnt labeled with color in the scheme. Since all other ones are there, the only remaining from the scheme is "alarm" - is that right? Where is supposed to go?

3) Current drain: The cars red/black is going to yellow on the radio, the cars red is going to red on the radio. However, if I understand the wiring right, red is battery and thus needs to go to yellow on the radio. So the two seem to be switched. However, the radio goes off with ignition and also on with ignition (as its supposed to do) and keeps stations saved (also as supposed to do) - I'm confues here. ....

4) The antenna plug is different. The car has an 90° connector (is that "ISO 150Ohm"?) which worked with the old HU. The new HU has a deep, straight, socket (is that "DIN 50Ohm"?). If both parentheses are "yes", I can get an Adapter. If no, any ideas?

Cheers
Max

jonathant

ToreB

Thanks for the reference jonathant.
The white wire is the antenna amplifier power supply. This needs 12V when the radio is on, and is often connected to the "ANT out" or "remote out" output on the radio.
The alarm wire is green in all the schematics I have seen. It could be that your car does not have an alarm/door lock control unit.
The red wire is permanent 12V, and red/black is switched 12V.
All these wires must be connected to the correct pin on your head unit, see its documentation for details.
The two FM antenna variants are called DIN and ISO. There are adapters available in most car stereo/hardware shops. Try google.
Cheers,
Tore

max3.2

Old Radio Plug
Hi,

thanks for the help already, I sorted some stuff out...
The presumable antenna power actually enters the antenna wire wrapping itself. That confirms what I find with spare parts. I connected this one to the corresponding radio port. Also, the car side antenna plug is DIN - an adapter for ISO was mounted and badly corroded to the wire, thats why I didnt realize it right away. So I don't need any new adapters. Those two fixes hopefully lead to some improve in reception.
The power and ground wires are also right now. Didnt have time for testing but I hope this overall gets me some improve.

The only thing I cant explain is the yellow wire. I attached an image for reference. Its clearly in the wiring harness of the car. I do have an alarm system (went off once, when the doors are locked but open). I dont know if there are different systems. Any further ideas with the supplied image? You can see the old radio connector, the power and ground wires connected anew, the white antenna power and then the misterious yellow wire still in the connector and thus unused is the previous years.

One of the POs routed some speaker wires from the old amps location up to the radio, removed the amp. The old DIN wire is still there. Just for the future or the winter season:
Is there an improve in soud quality if I use an external amp? Shall I use the original Blaupunkt or is there a better option?
Is there a way to get the now common cinch wires + amp on to the old DIN? (I found an adapter on you page Tore, is that the right one? Can you ship to GER?)
Do I need to change the speakers for a reasonable improve?

Cheers

max3.2

Also, if I compare the plug layout being GND,SW+,free, ANT, BAT+, YELLOW? this dosn't match the plug from the wiring in any way. But I feel like the plug and the old wires look original....

ToreB

Pictures are always good! The thick wire with the yellow end wire is the alarm wire. Isolate and tuck away.
You could consider to reconnect the wires to the original radio connector, and then use a adapter for connection to a modern head unit. here's an example of a suitable adapter.
Cheers,
Tore

max3.2

Well good idea but the plug kinda disintegrated while taking the picture so i removed it. I will isolate the yellow wire.
That should at least fix the current problems. Ill post tomorrow after testing.
As for a reasonable sound update, I' porbably postpone it to winter season.