radio or speaker problem

[four.rings@MCIONE.com]

Phil Rose <pjrose@servtech.com> wrote:


Yesterday--suddenly (things gotta start sometime, I suppose)--the Bose
stereo system (in '91 200q) began emitting a thundering, low-frequency
noise (thump-thump-thump-....). At first I thought something in the
drivetrain had crapped out. The noise went away for some minutes, but now
it's there almost as soon as (and whenever) the radio is turned on (makes
no diff whether AM, FM or CD). It has a deafening intensity--even at the
lowest volume setting. All connections at the back of the radio look OK.

Any ideas?

BTW, this is _not_ the loud, momentary whoosh of static that afflicts the
delta radio on my '89  when it's turned on. I can live with that one.
This, however, is unbearable. :(
>>>>>>>>>>>>>>>>>>>>>>>>>>

Phil, 

it looks like the final stage(s) of the power amplifier(s) are self-exciting.
This is usually caused by a parasitic positive feedback due to a lost ground. My
guess you have a burnt ground trace somewhere. Open it up and look at the PCB.
In most cases it is easy to spot.

OTOH if I were you I'd regard it as a perfect excuse to rid myself of the BOZO
HiFi wanna-be and install a real one (naturally Alpine comes to mind first) :-).

************************************************************
Igor Kessel
'89 200TQ -- 18psi (TAP)
'98 A4TQ -- mostly stock
Philadelphia, PA
USA
http://www.geocities.com/MotorCity/Garage/8949/homepage.html
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