Here is a quick fix to what I believe is a common Sega Naomi video problem. I've seen this happen on two Naomi motherboards I own, as well as on a Hikaru motherboard. Video looks to be smeared or ghosting, like in the picture below.
I don't know exactly how it happens or why (I'm too lazy to really investigate at this point), but the problem is with the filter board (not the motherboard).
After removing the filter board, turn it over and you'll notice a burned trace just under one of the long connectors. This pin is one leg of an RC network that goes to the VGA port, and then runs under the connector to another set of pins above it.
The fix is simple, jumper the two connectors to bypass the burned trace, and your video will look crisp as new.
Happy gaming!
Hello Dave! I I can not see that coming!
ReplyDeleteIn Japan, the board seems like a san KONOSUKE famous!
Thanks Piyo, I hope to learn enough to one day fix PCBs as well as Konosuke-san!
ReplyDeletethanks ive been looking for this fix for over 2 years.
ReplyDeletei removed 3 caps and replaced them that didn't fix it. replaced some resistor networks. still nothing.... but after a image search i saw what i thought was my own pic clicked on it and it too me here. i was disappointed that it wasn't mine then i read.... after a few moments of reading i ran to my Naomi 1 and looked at the filter board and bingo same trace fried.
what causes this???
also know anything about dim boards? i have dim board that doesn't seem to register or the Naomi doesn't see carts.
i have two carts and neither seem to work a non dim and a cart.
i cant aford much of anything so im hoping i can get this naomi working right. thank for bringing me closer
Hi werejag, glad my post helped. I don't know exactly, but I suspect it happens by plugging into certain VGA monitors that are already powered on.
ReplyDeleteAs for the dimm board, I've have one that is very touchy with its connector/contacts. I have to really press down hard and hold it down while powering on for it to recognize sometimes. Probably because I wasn't using screws to secure it. Other than that, there could a lot of other reasons why dimms crap out. Have you checked for battery leakage?
Best of luck.
found this
ReplyDeletehttp://img266.imageshack.us/img266/4047/biosmangiled.jpg
i removed the socket to expose the area to do a minimalistic repair.
http://img641.imageshack.us/img641/3676/s6300477.jpg
this might not be the cuase but it is something i found.
waiting on some 42 pin sockets to arrive from china now.
wish i can find a gdrom drive now
Good find. Common issue I've seen before when removing chips from sockets using a flathead screwdriver.
ReplyDeletecould this be why the carts arent reading?
ReplyDeleteCould very well be the case, or multiple issues. Again, my biggest problem has always been the connector.
ReplyDeletehey hey
ReplyDeletei have update
my replacement 42 pin sockets came in patched 4 traces to 3 bios pins
i have a fully working Naomi. n\
now i wish for a netdim board since i cant afford on any time soon.
thank you for the VGA fix you did help me out greatly.
juandelacosta@ hot mail.com if you ever want to talk.
Sweet! Congrats on getting everything working again!
DeleteThank you very much!
ReplyDeleteI bought a naomi motherboard for about 30 USD last week.
This unit also had the same video glitch as the first picture.
I fix it half a hour ago, the video output is clear now！