Noisy 246 image

[kasaski]

Recently picked up 2x 246s with some image noise issues, like a faint line pattern that slowly rises upwards on the screen. One works well enough while playing, I only really notice some noise while in the service menu on the grey background. It's not really an issue on that system but the noise pattern looks almost identical to the second system. The second is a lot more severe, you can see it pretty easily while in game, and the image is dimmer and slightly yellowed with the same brightness/contrast and colour settings as the first one, increasing the blue in the service menu helps a little.

It's definitely not my vga cable or IO, ive switched between a bunch of cables and 3 different i/o boards to make sure, and it's always exactly the same.
Anyone encountered this before and found a solution? I've done a inspection on each pcb and not noticed any damage.

I'll try to get some photos later today

 

[Franco23444]

Seems like a few Namco 246 B pcbs suffer from this symptom. I have a couple that do this. This happens because some one in the past has over or under volted the 5v line or shorted something, which tripped circuit protection on the main pcb. I did manage to fix one suffering this symptom by removing and replacing a diode on the Namco main mother board. I forgot which one though. One side note though, I have a 246c and 256 and they don’t suffer from this issue at all. I remember I had a soul calibur 2 Namco System 246 B pcb that had a clean image, until I shorted something and that faint rolling line showed up.

 

[kasaski]

thanks for the info, that should help point me in the right direction