White screen

[mbannick]

So, I have a famicom that I AV modded a while back and everything was working fine. Decided to redo the mod to get rid of the jailbars. While everything worked fine at first I got a white screen out of nowhere and its been like that ever since. My question is: did I fry the cpu or ppu? It's still showing a white screen on boot but nothing else. I cleaned out the cart slot and even re-soldered it to the board. As for the games I'm using, they all work on another famicom. Anyone have any ideas?

[P]

What games did you test?

[mbannick]

What games did you test?

Pretty much all of my games that I have on hand. Not sure what the deal is.

[P]

Could you name a few titles of them?

[fredJ]

I think that the PPU or CPU has died.  Maybe something got short circuited inside.
But it is hard to say for sure....

[mbannick]

Yeah it felt like something got shorted when I was testing it. Would a burnt cpu or ppu give a solid white screen? From what I've read it should not show anything at all. I guess I'll have to find a cheap donor nes or fami to harvest it's parts.

[P]

I can't recall that I've seen any fried PPU/CPU cases that produces a white screen, but I remember many cases that was initially thought to be a fried CPU/PPU that turned out to be something much simplier.

Can you hear any sound if you press start or something? It would be helpful to know the titles of some of the games that you are testing with (for various reasons).

[fredJ]

Yeah it felt like something got shorted when I was testing it. Would a burnt cpu or ppu give a solid white screen?

A broken PPU can show white screen.

[mbannick]

I can't recall that I've seen any fried PPU/CPU cases that produces a white screen, but I remember many cases that was initially thought to be a fried CPU/PPU that turned out to be something much simplier.

Can you hear any sound if you press start or something? It would be helpful to know the titles of some of the games that you are testing with (for various reasons).

No sound. I've just been testing anything I have laying around. All of these games work fine in a different famicom.

[P]

Someone said that you could check the resistance between the CPU power pin and ground. If the resistance is too low (as in the tens of ohm) the CPU is fried.