Thanks for your clarification, David!
Maybe I have recognised it from myself, maybe not.
It can't be know, because I'm Wacky.
For example, I realized TIP142 has reverse pin order compared to that don't-know-what-is-it-darlington.
I have used only my brain!
BTW, I have got some 2,4V zeners.
So I have looked at once again that little part of SS4.
I have surprised in some extent, because I have recognised that simple fact:
At MAGx5 there is nothing to do with that precious 2.37V zener with special thermal coefficients.
Because in this setting it is shunted by MAGx5 switch!
May be it is only news for me.
It is certainly has there because of eliminate trace shifting.
I have observed some annoying trace shift on scope, soon as I have got it.
But I have thought, if it will be in a good shape, I will carry out some calibration, and it will be gone.
I have soldered a 2.4V zener to its place.
It certainly has some effect on trace shift.
But I haven't satisfied.
I have got about 2V through it in normal position.
And in the light of the exploring above, there is exactly 0V on it. (With MAGx5 pushed.)
It needs further examining.
I think, I drink now some further beers for health of David and myself and everbody else, and I will let it down a bit.
Now, I listen some music rather.
Happy weekend for all of us!
Kind regards,
Gyuri