9 Attachment(s)
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.
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.
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>
