Noisy AT4033

saint gillis said:

  Dears, I'm repairing an AT4033, it works, but has a noise, a kind of highpass filtered little white noise.

  I've cleaned every part of the circuits carefully, replaced the electrolytic caps, replaced the capsule with a 100p capacitor, noise always there...

  I did my homeworks, here the schematic, any help appreciated, thanks :
http://www.sub-continental.com/diy/audiotechnica/AT4033.jpg

Click to expand...

saint gillis said:

Thanks everyone.
So I've shunt to ground every transistor's base and collector with the rc network, always noise.
Then I removed yellow and black psu wires supplying the preamp, and put a 4K7 load between them, and the noise was present...

Click to expand...

saint gillis said:

do you think I can put any low noise transistor in the regulator?

Click to expand...

saint gillis said:

  Dears, I'm repairing an AT4033, it works, but has a noise, a kind of highpass filtered little white noise.

Click to expand...