Hi Dieter

> the DAC MAX512 is defective (if you do not measure 0...+2.5V)

The DAC measures 0..2.5 V at the output, so it is ok.

> voltage is not doubled). Another reason could be a defective P26 or broken
> R109 that causes O23 to work as a simple buffer (amplification 1).

Bonggg! I am blind. I should have thought about, that the trimmer or the
resistors might be broken.

Thanks you for the hint.

Florian