Power supply problem???

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#21
Have these latest measurements been done with a "short-circuited" input?

If not: try that. Any rubbish coming from there will be most likely introduced by the 7815/7805's in the regulated PS part.

I've had some noise-problems with those in my first jlh-amp.

Some nice new electrolitic caps and paralled by MKP at two or three points will most likely help.

I'll try to point out where in a second:

change both the 100uF 16VW to 220uF 16VW (paralled with a 0,1uF MKP) and change the 10uF with new 10uF (Panasonic FC or Elna Silmic or so wouldn't cost you an arm and leg for these sizes)
 
#22
dutch diy said:
Have these latest measurements been done with a "short-circuited" input?

If not: try that. Any rubbish coming from there will be most likely introduced by the 7815/7805's in the regulated PS part.

I've had some noise-problems with those in my first jlh-amp.

Some nice new electrolitic caps and paralled by MKP at two or three points will most likely help.

I'll try to point out where in a second:

change both the 100uF 16VW to 220uF 16VW (paralled with a 0,1uF MKP) and change the 10uF with new 10uF (Panasonic FC or Elna Silmic or so wouldn't cost you an arm and leg for these sizes)
Click to expand...


Thanks, shall do, since I'm allready doing all the caps in the power amp, it's not too much to do these ones too! The input wasn't shorted. Might give that a try and see what the difference is. I did try disconnecting the Pre from the power amp, and the noise is still there in the speakers (didn't check it on the scope though).

Regards,

Tony.
 
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