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    @bradnic
    THANKS! That clears up a lot of the mystery.
    How do you know if your amp is fried? Symptoms?

    Sent from my smart phone using Tapatalk
    R135 /// 1990 Alpinweiß II 325is
    └┼┼┘ /// 1993 Black/Black Convertible (sold)
    ..24

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      Originally posted by Aleman View Post
      @bradnic
      How do you know if your amp is fried? Symptoms?
      -squealing in one or more speakers
      -distortion from the speakers at less than full volume
      -low static noise from one of more speakers even when nothing is playing in the headunit
      and of course
      -no sound

      Unfortunately to be 100% sure it's the amp and not the radio, you need to do the amp bypass or swap the headunit out. So it's not uncommon to fix a radio and then later find the premium amp needs service too
      Last edited by bradnic; 04-28-2019, 03:24 PM.
      I BUY/SELL REFURBISHED CM5907s & CM5908s

      HOWTOs:
      DB vert plastic bumpers
      OEM Keys
      MTech1 docs

      88 ix Lach/Card
      91 ic Calypso 3.1
      86 Cosmo 2.7

      OEM+ or bust!


      reelizmpro: I will always be an e30 guy.. I still do all of my own labor
      TrentW: There's just something so right about a well-built M20 in an E30
      e30m3s54turbo: I save my money for tuner parts.

      Comment


        I checked all the wiring diagrams and none of them covers the cm5908. Anyone know what the blue/gray and white/brown wires hardwired from the HU should connect to? Those colors aren't on the 89 wiring diagrams.

        Also, does the yellow/brown HU wire connect to a solid brown wire? And the blue/brown HU wire connect to a solid brown wire? The 89 diagrams only show the yellow HU wire connecting to yellow/red amp wire and blue HU wire connecting to blue/red amp wire.

        I see the yellow HU wire connects to the yellow/bk and the blue HU wire to the blue/bk. Once I get it hooked up and working I'll post a clear chart for the next guy.

        Sent from my smart phone using Tapatalk
        Last edited by Aleman; 05-08-2019, 05:51 PM.
        R135 /// 1990 Alpinweiß II 325is
        └┼┼┘ /// 1993 Black/Black Convertible (sold)
        ..24

        Comment


          Found out what the two mystery wires go to. Nothing in the E30.

          https://www.r3vlimited.com/board/sho...69&postcount=6
          R135 /// 1990 Alpinweiß II 325is
          └┼┼┘ /// 1993 Black/Black Convertible (sold)
          ..24

          Comment


            Originally posted by Andrew325is View Post
            I posted this in another thread I made, but maybe it makes more sense to post it here.

            Does anyone know the best way to do the amp bypass mod while leaving the original wiring intact? I know, needlessly complicated, but I don't want to modify the original wiring so I can revert back to stock without having to re-wire anything later.

            I have an amp that isn't good I'm going to attempt to use for this. The issue I've come across are the common ground speaker wires coming from the radio (this is a 90 325is with premium sound); the 2 yellow/brown and 2 blue/brown wires that combine into the single brown/black wire just before the amp connector. I read there shouldn't be common grounds for the speakers for the aftermarket HU (should be floating ground instead). So do I just connect the positive wires together inside the amp and leave the grounds connected as they are in the amp? Does the amp need to be powered on for the grounds to do whatever they need to do or should I terminate the power and remote turn on wires?

            I used my multimeter to test the grounds at the amp connector for continuity and they don't have continuity. They go through circuitry in the amp, and I don't know exactly how the circuitry is configured and what it consists of or what it does exactly.

            Maybe I should just install a floating ground adapter inside the amp.
            One way to do it is to use a ton of Tap Splice Connectors. You can pull the amp out, and then bridge from speaker loom to radio loom with one of these splice connectors on each wire. No cutting.

            Last edited by Aleman; 05-13-2019, 06:33 AM.
            R135 /// 1990 Alpinweiß II 325is
            └┼┼┘ /// 1993 Black/Black Convertible (sold)
            ..24

            Comment


              Originally posted by Aleman View Post
              Found out what the two mystery wires go to. Nothing in the E30.

              https://www.r3vlimited.com/board/sho...69&postcount=6
              yes they were for a 'dot matrix' feature. lots of speculation, but the post you linked to was probably close - just a way to display radio or cd track number info somewhere else, probably on the 5 series as mentioned. I've never seen evidence of such a feature back then, but it was certainly common in the early to mid 2000 timeframe.
              I BUY/SELL REFURBISHED CM5907s & CM5908s

              HOWTOs:
              DB vert plastic bumpers
              OEM Keys
              MTech1 docs

              88 ix Lach/Card
              91 ic Calypso 3.1
              86 Cosmo 2.7

              OEM+ or bust!


              reelizmpro: I will always be an e30 guy.. I still do all of my own labor
              TrentW: There's just something so right about a well-built M20 in an E30
              e30m3s54turbo: I save my money for tuner parts.

              Comment

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