I can only conclude that the problem is in the 400 MB. Anyone else here have any other ideas; am I all wet, or is that a correct conclusion?

Click to expand...

Well, if the problem moves with the board, that seems like a reasonable tentative conclusion. As additional confirmation, does the other imac now display properly? If so, it eliminates the possibility that there's a problem with the deflection yoke that kills some circuitry on the logic board. But if you now have two broken imacs...well, you get the idea.