bush 42" plasma no screen

[mali67]

Hi guys, i have a 42" bush plasma (pretty much a samsung)
when powered up the vs/va voltages jump to normal, then after a few seconds the voltage drops.
its the same on the control board , the vs-on drops off.

ive tried new ysus and buffer.

if i unplug the ribbon to the ysus the voltage stays on.

any ideas?