Bias adjustment for Jadis DA5

Could anyone give me a procedure to ajust the bias of the tubes (KT90 / 12AX7EH) of my JOR amplifier.
I called Jadis, and they asked me to bring them the machine, but its 1000Kms from my place. And the audio people I met in Paris said to me "do it yourself".

I know you helped a guy (mares-mares) 6 years ago, but I didn't find the pictures that could help me.

Thank you for any help

Jacques

Thank you Trelja for the advice. I first will wait to find long clips for my voltmeter and avoid to put my fingers in too irritable compagny.

Just one more question, probably obvious for you..
This bias correction has to be done with speakers and peripherals connected or not.. Its just a bit more complicated to do it with all the cables connected.

Best regards

Jacques

So Trelja, I did the job..
You are right, the worst was the opening..(I modified also the bottom, making 8 one inch holes in regard of the resistance and the potentiometers)

Talking about the job...The 5,62 resistances gives 6.2 when measured. The all four..(old age??)

The 2Ko potentiometer were a bit touchy.. Not so easy to make the step 2 of the bias equilibration (OmV between the two pin 3..) Nevertheless I put 145 mV bias (and less the 10mV between the 2 pin 3)

You are right the listening is incredible.. very clear and precise. At least with Jazz (Exemple Midnight Sugar, or Yim Hok-man drums incredible record). Then I went back to Piano and discovered that the "Lang Lang Chopin" (a Sony recording) is somewhat dumped..(etouffé, struggled... I don't know the english name)., It was better with other piano recordings. But neverthess, not so clear as usual..May be.. I have to let time to it...

Can this 145mV bias stay so or is it safer to go back to the traditional 110 mV bias to preserve tube longvity (KT90)

Thank you any way for your help
Jacques