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RE: Radio Noise
Fred,
Thanks for the reply. I will check out the feed thru capacitor. I was
amazed that Audi would get $120US and about 1hr labor ($64 at the dealer
in Seattle) for what seemed a $10 fix. I am also noticing that I can
hear my turn signals when on the AM band on the radio. The service
bulletin I saw talked about the A/C noise in the Audi/Bose radio - I am
wondering if the power line to the radio just isn't shielded correctly?
The tech bulletin also mentioned another symptom of the A/C clutch
voltage spike is the engine "misfiring". Vehicles affected were years 88
- 91 and the majority of the models.
Mike Miller
Bonney Lake, WA.
91 200Q (Pearl) mine
91 Caprice Classic (maroon) wifes
81 4k 5+5 (blue) - parting
81 4k 5+5 (white) 200k mi - for sale
74 F350 Camper Special with 10 ft camper.
>----------
>From: flderoos@mmm.com[SMTP:flderoos@mmm.com]
>Sent: Thursday, June 27, 1996 10:24 AM
>To: Mike Miller (Volt) (Exchange)
>Subject: Radio Noise
>
>Hi Mike,
>
>I had the same problem with my 1990 200TQ after having Audi replace
>the alternator to try to eliminate a high pitched whine. Anyway, I
>was able to solve it by cutting the wire to the AC clutch and adding
>a feedthrough capacitor. The capacity won't matter and probably the
>larger the better. I then added a 5 watt Zener (20- 25 volt )
>from the wire to the AC to ground. This will shunt the high voltage
>spike, when the AC clutch releases, to ground. I haven't tried it,
>but your idea of a large capacitor to ground from the clutch wire
>will probably also work. Feedthrough capacitors, however, are somewhat more
>efficient in removing noise. Give me a call if you have any
>questions. Try to keep the leads as short as possible and get the
>polarity of the zener correct.
>
>Good luck,
>
>Fred L. DeRoos, Ph.D.
>Senior Research Specialist
>3M Corporate Research Laboratories
>Maplewood, MN
>
>