NetBSD installation woes on Sun Blade 100

Hi,

i am having difficulties to install NetBSD 9/sparc64 on a Sun Blade 100.

After i boot the install cd, the kernel loads and after a few seconds
the screen goes blank. It happens very fast, so i can not tell what
and where it happens.

As this happens right after the boot of the install cd, i can not
install netbsd. There is no obvious way to pass boot parameters or
something to remedy this.

Both the FreeBSD and the OpenBSD sparc64 install cds don't show this
behavior, but i want to give netbsd a run, since it is supposedly the
only on to successfully provide a somewhat recent firefox for these
machines.

So i have already tried two monitors. They just blank and tell me they
do not receive a signal. I found some reports on the internet claiming
the same problem.

The machine is using an onboard Ati Rage XL (mach64).

Do i need to change the iso in some way and reburn it?