I recently got the much dreaded simasi mac upon booting my SE/30. According to everything I'm reading on line, this is most likely due to bad capacitors as they have a tendency to leak over time (or to just go bad due to age). There is one man on 68kmla who is selling capacitor kits for very cheap (starting at $10) but I have no idea about soldering. Does anyone know someone who would do it for me, OR does anyone have some helpful tips for doing it myself?
You've seen these?:
http://www.biwa.ne.jp/~shamada/fullmac/repairEng.html#SimasiMac
http://www.applefritter.com/node/20404#comment-44966
http://www.rjl.com.au/marketplace/Articles_show.asp?a=26
For a temporary fix for leaky capacitors, some claim you can wash your motherboard.
It would probably help if you posted a photo of your simasi screen.
And have you read though the threads linked here?
http://68kmla.net/forums/viewtopic.php?p=73484#73484
Take time to read through what I have linked on 68kMLA. It will give you a formal degree in SimasiMac and cap replacement.
The same fellow who has offered his SE/30 cap set to us on 68kMLA has also mentioned it on Vintage Macs:
http://groups.google.com/group/vintage-macs/topics?hl=en
And yes, I purchased two sets from him, so I can vouch for this set being a good buy.