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Thread: A4 B5 Stereo Volume Problem

  1. #1

    Default A4 B5 Stereo Volume Problem

    Hi all,

    I've been driving my shiny "new" 1999 1.8T A4 B5 over the weekend and have discovered an issue with the stereo. There appears to be something wrong with the volume knob, such that when you turn it any direction the volume goes from somewhat loud to immediately deafening.

    Turning the stereo off and back on resets it to it's loud volume, but again, turning it in any direction results in deafening volume.

    The gf has had the magic touch of pressing the knob in halfway and twisting it and it seems to be fixed, but I have managed to re-ruin it several times. No puns please!

    Has anyone had the same problem?

    Idea on how/how much to fix?

    Thanks.
    1999.5 A4 B5 1.8T

  2. #2
    Join Date
    Feb 2009
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    Glen Iris, Melbourne
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    common problem that i believe there is no easy fix for. i have basically the same car and the only way i managed to get around it was to replace the head unit lol.

    with mine, it would only do it when cold though. if i touched the volume straight after getting in the car, it would scream at me. but if i left it til later when the engine had come up to temperature, it would work fine.

    i also found that it wasnt the actual volume knob thats broken, it had to be the firmware, because changing the bass/treble etc with the same knob worked fine.

    alas, i didnt manage to find a fix. hope you have more luck

  3. #3
    Join Date
    Oct 2009
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    I have FRIDGE's old HU because mine was even worst (display broken, etc).

    I did a fair bit of research on this. The best answer I found is:
    It seems that the volume level is stored in a chip inside of the HU. Over time the chip lost it's ability to change/save the desired volume. Some also say that it is also related to the GALA setting, though turning off GALA does nothing on mine (err. FRIDGE's old).

    There are people who refurbish the units by removing the chip and putting a new one that will work (and apparently an uprated/upgraded one that will not break.. time will tell). but it is costly, so most people opt to change the HU. However, because of the speaker setup, ohms, amp location for rear speakers, etc... most people change the whole ICE setup.

    Doing a search in the ICE section will yield a lot of info.

    I hope this helps.
    2000 A4 1.8T Avant Quattro (MY99.5)
    2002 Subaru Liberty RX Wagon


  4. #4

    Default

    Thanks, I was considering swapping out the system for iPhone integration but I thought if it's a cheap, quick fix for the original stereo then I might as well cop that. How costly is that chip + labour?

    fridge:
    It says you're in Glen Iris. Do you also get horrible reception through Glenferrie/Camberwell with your '99?
    1999.5 A4 B5 1.8T

  5. #5
    Join Date
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    The going rate seems to be around $300+ mark. Heard it works but can't vouch for the service.

    For a whole lot less, I've heard of people who knows someone who knows someone () who can "repair" the chip. It would be wise to stay away from them.

    I have the same problem in mine but fortunately, mine defaults to a normal volume on startup and then full blast as soon as you touch the knob. But as mentioned by fridge, once the HU warms up it works OK. (Nothing to do with engine temperature, just the chip inside the HU warming up.)
    Last edited by broke90; December 7th, 2009 at 03:41 PM.

    Current:
    2004 A6 C5 Sedan 3.0 V6 Quattro
    1999 A4 B5 Avant 2.4 V6 (Unreg)

    Retired:
    1990 100 Sedan 2.3
    1991 90 Sedan 2.3
    1999 A4 B5 Sedan 2.4 V6
    2005 A6 4F Sedan 3.2 V6 Quattro

  6. #6
    Join Date
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    I've noticed that with summer here, it takes a lot less time to "warm up".
    2000 A4 1.8T Avant Quattro (MY99.5)
    2002 Subaru Liberty RX Wagon


  7. #7

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    Found a really good explanation of the problem:

    http://www.erta.ru/review/chorus-problem_eng.shtml

    No mention of a clear solution anywhere.
    1999.5 A4 B5 1.8T

  8. #8
    Join Date
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    Nice find!

    Somebody went to great lengths to really find out the problem.

    And they do actually offer a solution... not a DIY, but a solution nonetheless:

    "
    It is very easy to diagnose this defect. If you see the fault of all the controls ("Volume", "Balance", "Fader", "Treble", "Bass"), it just means that the control knob is out of order. If the problems take place with the volume control only (all the other controls operate well), it indicates that the EEPROM microcontroller has worn out and you have to replace the chip.
    To liquidate the recurrence of this failure after the microcontroller replacement we continued our investigation. We managed to unassemble the internal program of the MC68HC05 microcontroller, which is used in these autoradio models. All the operations with the 01A8h cell were located. Then the program was changed, and as a result all these EEPROM cell operations were successfully readdressed to the random-access memory (RAM), which resource is unlimited. Now we buy the "clean" one-time-programmable microcontrollers and program them with the object code of the revised program. After the assemblage of the reprogrammed microcontroller to the autoradio the recurrence of volume control problems is absolutely out of question! The improved program operation can be easily checked by the microcontroller output VPP1 voltage during the volume level changing."

    So, changing the chip for a "reprogrammed" one will do the trick of never failing (or so they claim) since they have rerouted the saving of the volume changing to the RAM which has unlimited resources.
    2000 A4 1.8T Avant Quattro (MY99.5)
    2002 Subaru Liberty RX Wagon


  9. #9
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    my a4 has this problem... to get around it, I get to a soft part of the music, turn it down until the volume shoots through the roof and then crank it down again. Usually I only have to do it once. If you do it on a loud section of music you'll blow your speakers quick and probably your eardrums along with them!
    2011 Audi A6 3.0T S-Line Phantom Black/2-tone Valcona, 19" B8 S4 Rotors 160K
    2008 Range Rover Sport TDV6 white/black leather, 20ís, h/k 318K
    1999.5 Audi A4 1.8TQMS avant, Phantom Black/black 376K
    1990 Nissan Pintara TRX 5MT, a few mods 439K!!

    Gone but not forgotten
    2000 Audi S4 6MT, nogaro/black Stage 3-
    2001 Audi A4 1.8TQMS ming blue/slate 373K

  10. #10

    Default

    Oh, sub-question to this is, would a smart bloke with a soldering iron (obviously not me) be able to wire in an ipod adapter into a line-in or RCA port at the back, if there is one?

    I used to use a casette adapter on my old car but you get crap sound and I'm pretty sure it's only one channel.
    1999.5 A4 B5 1.8T

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