Video out, Bad Card?

Someone donated an older Compaq Deskpro 4000. Using a known good
monitor we can get NO video, just blank screen at startup. Power
is on and HD appears to be turning on.

Is this a bad video card? How can I determine this? Anyone know of
a cheap source for a replacement? Took case off and system appears
to have separate video card from MB. Or is this a bad MB?

Thanks for any helpful information.