FET3 Preamp - problèmes électroniques

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FET3 Preamp - problèmes électroniques

Message par viking » 17 Juin 2016 17:28

Salut! Pardonnez-moi pour écrire en anglais. Je serai également reconnaissant pour les réponses en anglais et en français.

My ovation has a FET3 preamp http://www.ovationtribute.com/Ovation%20Schematics/Ovation_FET-3_Pre-Amp_Schematic/Ovation_FET-3_Pre-Amp_Schematic.html which tends to make hissing noses and I am thinking about disassembling it and see if anything is wrong. There is also a little bit of 50Hz hum, which disappears when I touch ground (the metal house of the Jack cable).

The way I understand the diagram some functions are:
R2 = Equalizer "Treble"
R3 = Equalizer "Bass"
R5 = Volume
R7 is probably to set the operating bias for the FET.
R8 = Equalizer "Mid"

Some capacitors are electrolyte type (C3 and C6) which tend to degrade over time.

My questions are:
* Is noise common in FET amplifiers?
* Is it likely that the noise is due to old capacitors?
* Have any of You tried to disassemble A FET preamp - are there instructions to follow?

Thank You very much/Mercí beaucoup.
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