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928 stereo

 
Old 03-19-2019, 03:58 AM
  #1  
Mixtli
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Default 928 stereo

Hi guys,
I'm trying to replace the faulty radio in my 1900 928S4. I have a new unit which I've fitted and powered up ok but I can't figure out the speaker connectivity! The old unit had a round socket for the speakers and the diagram on the old radio had s label in the top has 'Sortie Preamplificateur' labelling it. I think this means Pre-amp output.
Did this car come with a separate amp? Am I going to need a particular type of radio or does anyone know a way around this?

Thanks!
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Old 03-19-2019, 06:49 AM
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R.Pires
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Hi,
I will wait for the experts to clarify but I think that the cars that have an amplifier it is located inside the cover near the passenger seat.

Regards
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Old 03-19-2019, 07:20 AM
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jpitman2
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Your new radio will have a speaker out map - many makes use the same colours now. Try to locate the speaker wires - maybe pull the door cards and get the speaker wire colours, or even look in the wiring diagrams for your year, verify a couple. Usually speaker wires have one plain wire colour, and the other is same colour with a stripe, eg blue, and blue/red, or blue/black etc. One other way is when you think you have a pair, use a dry cell battery and connect one wire firmly, wipe the other wire over the other pole - a speaker will give you a static type noise if your guess is correct.
Some modern radios have both speaker out leads, and connections that need to go to an amp - JVC do this with upper level models - can recommend the DV series - plays multiple types, CDs and DVDs, and will play movies, cooling fan, equalizer.
Sing out of you dont have wiring diagrams.
Guessing its a 1990...my last wiring diagram is 87. There are 3 radios shown, one with a round connection , 7 pin going to booster, but no details of whats what. There seems to be some consistency in the speaker wiring across all 3 units - final wire colours are the same for all versions.

Rear left - BR and GN
rear right - BR/WS and GN/WS - brown, green with white stripe?
front left - BR/WS and BL/WS
front right - BL/WS and BR/WS fronts are doors.
The hifi version has tweeters hanging off the door speakers, and there are separate B-pillar and rear speakers. The rears in this case are slaved off the B-pillar speakers with a crossover? One wire out of the HU is marked '1.0 WS' looks like power the aerial amplifier.
HTH
jp 83 Euro S AT 57k

PS - the code for white changed from WT to WS as of 85 MY on my diagrams - German being Weiss probably. Where there is a fader as well as the amplifier the diagram gets very complicated, but its probably not as bad physically.

Last edited by jpitman2; 03-19-2019 at 09:34 PM.
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Old 03-19-2019, 08:49 AM
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Mixtli
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Thanks! That's great starting information and confirms my thoughts that it has a separate amp. I think I'll be looking to bypass it and just connect the speakers directly to the new radio. If anyone has any detailed information about accessing the pre-fitted amp, I'd be very grateful! Where is it and how do I get at it?

Thanks again!
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Old 03-19-2019, 02:01 PM
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dr bob
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The carpeted cover next to the passenger seat hides the aux amplifier and some other critical pieces like the fan controller and a engine controls diagnostic plug. Power for the head unit passes through the compartment too; you'll want to carefully evaluate that power delivery especially if you do end up using the speakers from the head unit and no external amp, as the head unit will need a lot more power than originally supplied. The original speakers are impedance and frequency response matched to the amplifier too, so your upgrade project will include new speakers plus new wiring from the outputs in the new head unit to them.

Keep as many of the original pieces intact and store them carefully away as you replace them with modern bits. If you choose not to save them, PM me and I'll add them to my spares collection if they are still in good shape.
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Old 03-19-2019, 02:16 PM
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jetson8859
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Crutchfield has adapters that can be used to go from the amp wiring to standard wire ends. This keeps you from having to clip the ends of the speaker wires if you decide to use the original wiring.

I replaced the original amp with a small Boss Amp that fit in same place and ran a couple of pre-amp out cables under the carpet to the new head unit. I also replaced all speakers but utilized the original wiring.

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Old 03-20-2019, 07:03 AM
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Schocki
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Originally Posted by Mixtli View Post
Hi guys,
I'm trying to replace the faulty radio in my 1900 928S4. I have a new unit which I've fitted and powered up ok but I can't figure out the speaker connectivity! The old unit had a round socket for the speakers and the diagram on the old radio had s label in the top has 'Sortie Preamplificateur' labelling it. I think this means Pre-amp output.
Did this car come with a separate amp? Am I going to need a particular type of radio or does anyone know a way around this?

Thanks!
Was your old radio an original Blaupunkt unit? If yes, your car was possibly connected to the amplifier via the (back then) standard DIN connector. The wiring is unique in our cars, the original Blaupunkt amplifier service as a frequency splitter for the rear bass speakers too. On top of everything else the speakers are not using standard impedance of 2 Ohm. Not very compatible to many radios and aftermarket speakers. Below a picture of a Mini-ISO to DIN Adapter.

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Old 03-20-2019, 09:09 PM
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Randy V
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Originally Posted by Mixtli View Post
Hi guys,
I'm trying to replace the faulty radio in my 1900 928S4...
Did you get here in a DeLorean with a Mr. Fusion power plant?


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