MAMEWorld Forums - The Loony Bin

> OK, here's a weird thing. When I first power the board up, the video appears mostly
> blue-green. But when I touch U5-pin27 to ground just for a second, the screen blinks
> and snaps into more of a full-color mode still fuzzy with lines only the background
> appears black and the lines are white. It stays like this until I power down.
>
> When I touch and hold U43-pin17 to ground, the screen goes almost completely white
> for a second or two until the graphics refresh and the white lines seem to lighten up
> but the screen still looks very static-y. When I run the CPU test while grounding
> U43-pin17 it still fails but this time it shows some of the ROMs to be bad and stops,
> leaving the RAM untested. Without grounding anything it tested the RAM and then
> stopped. The original results remain the same when not grounding anything.

Sounds more likely to be dodgy VRAM then.

> That VRAM source is a good price and he combines shipping! But the speed on the
> original RAM chips was -10 and the ones on eBay are -15 (slower). Would that make a
> difference?

Not in this case. The 150ns parts are well within the timing limits of the video hardware so they'll work.