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Measuring A Capacitor

I have a preamp (NAD 1155) that has a hum problem. It started when I got a new turntable, so I thought it was a TT grounding problem. But no... The preamp's phono section hums every time it is selected. Even if there is no phono present. All the other inputs are dead quiet.

Anyway, a fellow 'goner thought it is a capacitor that's going 'round the bend. I'm willing to take my volt/ohm meter, and find the offending component, and replace it. All I know about capacitors is that they are measured in picofarads, and they discharge their energy in bursts, when it's requested.

Any help in this regard is much appreciated. I have a mountain of vinyl waiting to be played.

TIA

Lee
licoricepizza

Showing 2 responses by danmyers

danmyers
135 posts
 
Yet another reason why I gave up on LPs: phono pre-amps :)

Lee, the tin foil must be grounded to be an effective shield. Simplest way to do that is to use an alligator clip from the a known ground on the (pre/integrated)amp (chassis ground lug, chassis, outside of a RCA jack,etc) on one end and then clip the tin foil on the other. That will create an effective EMI/RFI shield... which still may not be your problem.
danmyers
135 posts
 
Excellent! Make sure the foil is grounded and it will make an excellent EMI/RFI shield (or even a Farady cage if you're so inclined).
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