Hi all.

I'm new to this group and I hope someone can give me an advice.
I was modding a PC-Engine videogame system to have a RGB video output
(by
getting signals I needed straight from the mother board of the game
system). It's not my first time in modding but unfortunately something
went wrong and, even if the mod is working, the video output is not as
it
should be. I guess a video memory bank of the console got fried.

Some sprites are missing and backgrounds in the games look scrambled.
it's
not a malfunctioning of the mod, because the same problem is visible by
using the normal RF output of the console.

My question is: how can I check which is the faulty component? Should I
use a multimeter? How is this kind of testing done?

I'd be glad of reading some howto if anyone wants to point me in the
right
direction, but I'd also love to get a specifical answer.

Tanks a lot.