Looking for Krell KAV-400Xi schematic / service manual

[richloh]

I’m glad they are able to be of use to people. I get lots of help from the folks here and it’s good when I can help. I’ll reach out to you once I’m able to email you some good clear scans.

Dan

Hi Dan,

Your contact can only be correct that 400xi power schematic is same as 300il ... Peter's shared that he asked Krell then who provided them and in turn nicely shared here indicated the same.

Thanks again to both you and Peter in helping out .. with appreciation.

Cheers.

 

[richloh]

Krell KAV-400XI repair update:

• All electrolytic capacitors including the 8 6800uF psu are out of spec. (measured 10u instead of 47u)
• one of the input circuit transistors is out of spec (bc847), replaced both.
  • dc unbalance is gone now

All components are ordered and probably available next week

Hi,

Read with interest on bc847 and dc offset and deciding if I should also try ... mine read 0 and 20mA which is fine and while Dan aka saabracer 23 shared his measuring 3mV which is certainly perferred.

Kindly shared what was measured before and after for both channel.

TIA and cheers.

 

[richloh]

• one of the input circuit transistors is out of spec (bc847), replaced both.
  • dc unbalance is gone now

Oops .. just check schematic and saw many bc847 .. will not proceed to try change/find out for jusr 20mA on one channel then. Cheers.

 

[richloh]

richloh
Thank you.
]What did you do with 4x op amps (opa604au) in preamp section ?

Hi gogg, no plan to do so but the 2nd local electronic engineer suggested opa627 as he believe only FET works vs his prefer ad797 .. if adventurous, you may also consider fast recovery diodes as done by some but I may have burnt out or simply already amazed with the SQ of this vintage krell at least in my friend's mentioned audio system not to pursue further .. especially not capable to diy i.e. more $.

Moreover, seems that some has high praise for stock 604au and I do believe that it is all about matching that "better" parts but more details in following link if you wish to venture:

https://www.head-fi.org/threads/opa604-to-opa627-in-shanling-cd-s100-mkii.73648/

Cheers.