I have found the problem.
Some of the wires from PSU to busboards were faulty. As a coincidence
the wires to both PSU`s were faulty.
I unplugged these wires to measure voltages on the PSU and both LED`s
lighted when plugged in.
Thanks for your warnings. Although I do not have a electronics degree
I take full precautions.

--- In Doepfer_a100@yahoogroups.com , <hardware@...> wrote:
>
> > I noticed that in my self-made cabinet the PSU`s only give +12v
> > (the LEDs of -12v on both PSUs and on the busboards don`t light
up).
>
> So the A-100 modules cannot work as both +12V and -12V are
necessary.
>
> Probably the bus boards are not wired in the right way to the power
supply
> or the power supplies are defective. But it's very improbably that
both PSUs
> are defective. How about the control LEDs of the PSUs
>
> > Opposed to the G6-case.
>
> > I think I connected the busboards to the PSU as it should be.
> > It`s strange that it happens on both PSU`s.
> > Does anyone know what the problem might be (as I`m no technician)
>
> I know this warning might be boring for some of you but I will
repeat it
> again:
>
> If you are not familiar with electronics I'd strictly disadvise to
built a
> self-made cabinet with the standard PSUs. There is danger to life
if you
> make a mistake because of the mains voltage! I'd recommend the new
DIY kits
> if you want to built self-made cabinets. The PSUs of these kits
have no
> dangerous voltages inside. In the worst case the PSU and/or modules
will be
> destroyed but you will survive !
>
> Best wishes
> Dieter Doepfer
>