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Thread: Radio Head Unit (EU 1992) Repair and Capacitor Replacement

  1. #1
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    Lightbulb Radio Head Unit (EU 1991) Repair and Capacitor Replacement

    A fellow NSX driver approached me after fixing all three of his amplifiers reporting issues with his radio. It worked but when listening to stations they were distorted and he mostly used it together with a CD changer adapter. The unit arrived last week, with an interesting modification to supply power to an extra set of speakers but nothing to worry about. Time to grab the active speakers, a cassette and a CD changer for a test run.


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    back
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    bottom

    Radio tuning and sensitivity were fine. The sound was indeed distorted - an effect that wasn't audible when playing cassette (which worked fine - including reverse and track skip so no belt replacement required) or CD. The sound got better after warming up but then the CD playback, which was working on one channel only, completely dropped out - suspect here is the OP amp near the CD changer socket as it's often affected by acid creep.
    Since the distortions were only present when the radio was playing it couldn't be the Z-diode from the last radio repair since that affected all sound sources equally.

    Next step was opening the case and investigating the PCBs for damage. It's the typical European RDS NSX radio with the extra large voltage stabilizing capacitors that leak substantially.
    Two capacitors had blown and, three where bulged and the two large ones leaking. The capacitors on the small power where leaking too but no damage had happened to the PCB yet.

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    bulged and vented capacitors
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    soaked connectors and OP amp
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    large leaking caps

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    acid leaks on the PCB ..
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    .. underneath the flat cable connector ..
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    .. and on the power board

    To ensure a proper repair, the CD changer and the left flat cable connector were removed and investigated. Since there was no corrosion beyond the soldering points they were deemed fit for service and later re-installed. The OP amp and all contaminated silk screen was removed, no damaged tracks observed and everything cleaned, including the connectors.

    <to be continued>
    Last edited by Heineken; 20-11-2021 at 12:36 PM. Reason: typo
    1997 JDM Custom Order AT VIN 1400005 - Stock
    Heineken's Garage

  2. #2
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    Default

    A new OP amp, cleaned connectors and new capacitors were installed. Since only the larger capacitors are replaced (identified by venting marks on top) the small one on the middle PCB, under the metal shield, was replaced, too (no image). Note that the so-called semiconductor crisis isn't only about these but regular parts, too. Some of the capacitors have doubled their price in the last six months ..

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    new operational amplifier
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    re-capped lower PCB
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    .. and power board

    After successful re-assembly the unit was powered up and played without any issues. Stable sound during radio usage, both channels when listening to CD and no warm-up effect. Summing it up, the dying capacitors where the reason for the radio distortions and the CD changer OP amp died of being soaked in acid for too long.

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    old capacitors
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    strengthened CD player port
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    back in working condition

    I'm happy to announce another working OEM radio looking forward to supply his owner with hopefully many trouble free hours to come
    1997 JDM Custom Order AT VIN 1400005 - Stock
    Heineken's Garage

  3. #3

    Default

    Nice work !!!

  4. #4
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    Thank you very much
    1997 JDM Custom Order AT VIN 1400005 - Stock
    Heineken's Garage

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