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Mid-band oscillation...Power tranny?

12/30/2004 12:43 PM
piresito
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Mid-band oscillation...Power tranny?
Hi!  
I have a oscillation problem that seems very strange.  
 
The oscillation should be around the 2khz frequency, and I think the problem comes from the power tranny because when I turn on the amp (stanby mode, only heaters are working) I can ear the PT vibration that seems to be the frequency that the oscillation is when I turn on the power amp. The oscillation change in frequency and in volume when I touch the chassis.  
 
The transformers (output and power) and power supply (the power supply has active regulators) are on the same chassis (shielded) and the power amp is in another pcb (witch is 15/25cm away from the trannys chassis).  
 
The power amp was push-pull and I recently modified it to single-ended (to see if the problem could be related to the Push-pull topollogy) but the oscilation still in there.  
 
Can somebody help me?

 
Replies:
neil Hi,It could... -- 12/30/2004 12:41 PM