Retro Computing Corner: SimasiMac Fix!
Author: SmellyGeekBoy | Date: April 21, 2008
Last time in Retro Computing Corner I introduced you to my two classic Macs, an SE and an SE/30. I also revealed something else to the world - a little fault common to the SE/30 known as SimasiMac. Well, today I’m going to tell you how you can fix it very easily, provided, that is, that you’re fairly proficient at soldering.
But first an introduction - what is SimasiMac?
Here’s a little explanation thanks to Jag’s House, a specialist in all things classic Mac:
Simasima means a zebra-like stripe pattern in Japanese. OYU!(HHD00612@niftyserve.ne.jp) and Shunsuke Suzuki(VZD03711@niftyserve.ne.jp) nicely named Macintosh SE/30 with this problem SimasiMac. We SE/30ers in Japan call it SimasiMac.
Basically, if your SE/30 isn’t starting up and is displaying either horizontal stripes or a checkerboard pattern, you have the dreaded SimasiMac. A very easy way to find out is if you leave the stripes on screen for 10 seconds, turn the Mac off for 5 seconds, and turn it back on, it should boot up as normal.
Eventually it’ll end up completely dead to the world like mine, with a whirring noise and not a lot else. It’s time to dig out the soldering iron.
First up, you will need to dismantle the case and whip out the motherboard. There are plenty of guides around on how to do that, so I won’t go into detail here. If you’re not comfortable going this far, please don’t proceed any further - get someone who knows about electronics to do this for you. If you screw this up, your Mac will be dead forever!
Next we will need to locate capacitors C6 and C7. If you place the motherboard down with the rear connectors facing towards you and the RAM / ROM facing away, they will be on the side nearest to you, towards the right. You will need to desolder them with a very hot soldering iron (not a cheap crappy one like mine) with a fine tip, by heating up the little metal pads either side and slowly prising them up with a screwdriver.
Then we simply solder the new ones in place - C6 needs to be 1µF 50V and C7 needs to be 47µF 16V. These aren’t particularly common ratings so you will need to order them online.
As you can see from the picture above, my soldering is absolutely rubbish, but they are making good electrical contact and that’s all that matters to me (I did clean the joints up a bit after this picture was taken). You will need to take special care not to overheat the capacitors or the motherboard itself, or any other components nearby, as the heat can damage them.
Also, make sure that the sides with the stripe (the negative side) are pointing towards the left, as they were on the original capacitors. You won’t blow anything up by getting them the wrong way round, but you will curse yourself when you have to desolder them again.
Finally, we can pop the SE/30 back together and fire it up, just to make sure that everything’s OK… I got the reassuring “bong”, and then the usual startup screen. If you get this far you can turn the Mac off, carefully put it back together, and get on with your life.
See, that wasn’t so hard was it!
Oh, and I hope you took the time to clean out the dust bunnies while you were in there… 
