Aragon 24K Volume control noise and dc

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rickcl

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Joined 2003
#1
Hello. I have an Aragon 24K preamp that has a little scratchiness in the volume control in the first 1/4 turn on the left channel. I had a cheap linear pot. so I stuck that in circuit and it did the same thing. I took the original Noble pot. apart and cleaned it. It's fine.

I did measure -49mv across each the sliders to ground. I did stop all the noise by soldering in a couple of 4.7uF NP caps in series with the slider.
There are a couple trimmers close to the line amp. I was wondering maybe these are offset adjusts.
For ref: power supply output: -24.70 and +25.32

Thanks all! I am stumped....
 
#2
Sounds like input bias current of the following amplifier stage is at fault, which would indicate either a leaky existing coupling cap or none being present at all (which would be a design issue). It's hard to tell more without a decent idea of what the circuit looks like. Seems to be a discrete affair.
 
#6
I have the same issue going on with this pre-amp ... so I'm also looking for the Aragon 24K schematic. As a side note I just saw an Aragon 4004 with a turn-on delay issue on Ebay today...curious I had that problem as well. The Mondial issues are rare but I seem to be consistent.
 
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