I have a Macintosh SE/30 that I'm trying to bring back to life. When I power it on, I get the dreaded horizontal stripes. Or, zebra stripes. Also called Simasimac.

I have re-seated all of the socketed chips. Pulled the ROM SIMM out, cleaned it, etc. Pulled the RAM out...

There are two standing issues that I can confirm. One, the battery is dated 1989 and it only registers 1.0v. It's normally a 3.6v battery. So it's safe to assume it's just about dead. :-)

Second, I believe most if not all of the capacitors have leaked. There is a green "fuzz" all over the board. I can provide pics if needed. Just about every chip close to the surface mount caps are green and fuzzy.

So at the very least I believe I will re-cap the board.

Which brings me to my question. According to some YouTube videos I've seen and this website (http://lowendmac.com/brierley/09pb/simasimac.html), they suggest washing it with water.

That seems a little drastic but I have to admit, it sure would be faster. I thought about even putting the board in the dishwasher.

I seriously don't know if I could get a brush under each IC and clean off the fuzz. And I really don't want to de-solder every chip.

Should I wash it? If so, how? Submerged into a hot bath of dish soap or should I put it in the dishwasher?

I realize that if I do wash it, I'm going to give it 7-10 DAYS before I attempt to power it on. Plus, it would get a lot of outside air time so the breeze could help dry it out. (been hot and dry around here).

Suggestions appreciated.


  • It's in portuguese, but has some pictures showing the process. See: msxpro.com/f1xdj.html
    – adriano
    Nov 5, 2016 at 11:19
  • I've put several motherboards through the dishwasher with no soap. Pull all the socketed ICs and wash separately. Results are good. I use a hair dryer to dry them out quickly. Cap leakage is often alkaline, so remove with a toothbrush and white vinegar, then clean with alcohol.
    – Brian H
    Nov 24, 2017 at 17:38

3 Answers 3


Your capacitors are definitely bad, you should get that goo off of the board asap, however the damage may already be done. you might consider using a tooth brush while you're at it

I've washed boards and powered them up same day after drying them with a heat gun, but be careful, a heat gun will melt stuff if you leave it in one place for too long.

Another way to purge water from a board is to get a can of diethyl ether (starting fluid from an automotive store) and spray the board down with it, it will drive out the water and actually do some cleaning in the process, might be a candidate for getting under some of those chips. Be very careful with this though as ether is quite flammable, and can make you pass out if you breath it. I've also done this and powered up boards same-day.

Unfortunately if things are getting fuzzy it's been sitting there a while.

When you desolder the old caps, I would suggest investing in some copper braid and some desoldering tools, the first (and only time) I attempted to recap a mac board I ripped a number of traces right off the board, when removing the caps.

Heres a reference on the capacitors that need replaced: http://maccaps.com/MacCaps/Capacitor_Reference/Entries/1989/1/19_Macintosh_SE_30.html

Also the guy that runs that website has reasonable rates for cleaning and new caps if you want to ship him your logic board.

  • Thank you. That was some excellent advice. And you saved me from having to ask my next question on where to find the cap values. :-)
    – cbmeeks
    Nov 8, 2016 at 13:26
  • UPDATE: I decided to wash my board after removing the caps. I used distilled water and a mild soap. Board looks clean but the "fuzzies" are still everywhere. Many IC's have some green on the pins. Most of the large IC's look clean. It's mostly the smaller ones. So, I'm debating finding replacements for them all. I just hate seeing a vintage board become un-fixable. :-(
    – cbmeeks
    Nov 21, 2016 at 15:42
  • Starting fluid usually contains a bit (or quite a bit) of substances other than diethyl ether, which might not be so computer-friendly.
    – hobbs
    Aug 15, 2018 at 17:59
  • depends on what brand you buy, which is why I specified diethyl ether. But even with those extra ingredients I've saved a few things. My kids spilled a milk in my 2009 macbook pro once, and rather than completely take it apart and clean each part I simply took the back off, removed the battery and blew a whole can of starting fluid through it, keyboard and all. This was several years ago and It still works to this day. Your Mileage may vary, but I've never had a problem cleaning circuit boards this way. Sep 10, 2018 at 15:46

I recently cleaned my amiga 3000 main board using denatured alcohol and q-tips. It took a few sessions over the course of a few days, but the board looks brand new. Of course, you have to be careful around stickers or possible sharpie marker writing, or wax pencil marks... but if you take your time the results can really be astounding.

  • I have nearly 70 vintage computers. That's what I normally do as well. I scrub them with 99% IPA. But this particular board is covered. But, I may pass on the dishwasher method.
    – cbmeeks
    Nov 5, 2016 at 6:52
  • @cbmeeks When I read "IPA" I first wondered why you were using beer :D Aug 14, 2018 at 17:36
  • @WayneConrad Nah...I wouldn't waste a good IPA by pouring it on a motherboard. Unless I already had about 5-10 of them. lol
    – cbmeeks
    Aug 15, 2018 at 18:11

I once tried to get rid of electrolyte residue on an SE/30 board. After recapping the board worked but after flooding it with denatured ethyl alcohol and carefully brushing it with a toothbrush, it was dead. Simasimac. (Yes, I let it dry overnight.)

I suspect that my treatment allowed liquid to enter some ICs and did irrevocable harm.

  • 1
    "I suspect that my treatment allowed liquid to enter some ICs and did irrevocable harm." - Water or alcohol should not cause harm if it is removed afterwards. I repaired many PC motherboards by washing in hot soapy water while scrubbing hard with a toothbrush, then drying out in front of a heater until nice and toasty. Worked every time, even with severe battery leakage (though sometimes I had to repair tracks that were corroded away). The key is to dry the board thoroughly (with plenty of heat to drive out moisture) before re-applying power. Aug 13, 2018 at 0:47
  • I'm not aware of any IC's on an SE/30 board that would allow liquid INSIDE them. They should be sealed. Unless the IC is severely damaged. Also, I personally recommend using 99.9% IPA and not the denatured stuff. But that's just me. I think the denatured stuff has some kind of chemical inside to keep people from drinking it. Maybe that stuff left residue behind?
    – cbmeeks
    Aug 13, 2018 at 12:20
  • @cbmeeks: Most pins of the larger chips showed copper rust. I suspect that this corrosion already wandered inside the plastic casing and maybe allowed accelerated chip death through my treatment. I successfully recapped and restored multiple IIci, SE/30 and LC boards as well as IIci cache-cards but every time only with drips of DEA and the toothbrush.
    – PoC
    Aug 13, 2018 at 19:20

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