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Posted to sci.electronics.repair
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Capacitor Shield ?
Jeff Liebermann wrote:
On Sun, 8 Nov 2015 18:59:21 -0800 (PST), wrote:
I'd agree with that.
Probably there was a hum or buzz in the low level magnetic phono
circuits which are very sensitive.
Mark
Something must be wrong. Nobody ever agrees with me.
I didn't even notice the wire.
Greg
Marginally related anecdote: The easiest way to tell what something
does is to remove it and see what breaks. I used to own a 1970 Land
Rover Series IIa. In order to replace the spark plugs, I had to first
remove a steel "heat shield". This bothered me as I could see no
reason why a heat shield was necessary in such an open and drafty
engine compartment, with nothing nearby to protect. So, I removed it.
Everything was normal until I hit 57 mph, when the engine compartment
turned into a giant low pitched whistle, which made enough noise to
attract the attention of all the nearby drivers on the freeway.
Apparently the "heat shield" detuned the engine compartment so that it
would not whistle at operating speeds.
Remove the amplifier shield and see what happens. My bet is some low
level hum, that could only be measured on instruments, but which would
affect the advertised noise levels.
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