Sansui AU-20000 No preamp signal...

[shapeshifter]

2SA726 & 2SC1313 > Do you have any recommendations which type I should use?
I found this replacement list:

 

[Hyperion]

That seems ok

Double check with the list in Solid State sub forum "Top Ten Worst Transistors....."

https://audiokarma.org/forums/index...ilure-prone-whatever-and-replacements.731653/

 

[shapeshifter]

Thanks, John!

After a bit more cleaning I first thought the noise was gone, but it came back....
https://www.dropbox.com/s/tg8v6wwoh0aspz1/IMG_4242.m4v?dl=0

It is mostly on the left channel, but sometimes on the right too...

 

[shapeshifter]

So the transistors arrived yesterday. I replaced the suggested ones plus two caps (one was already a replacement so I decided to replace both channels with WIMAs). I also biased it to factory specs...
And now everything is nice an quiet at idle and the amp works great!! I have a AU-505 in my livingroom that I really love, but I have to admit this thing puts it in its right place.

Thanks for all your help!

 

[Hyperion]

Very well done! - this is great news.

 

[shapeshifter]

Thanks, John!
Now, this wants me to try and replace those AU-505 trannies to see if I can get closer to the AU-20000 (I already recapped it a while ago, when the power filter cap failed.)