Mac IIsi...botherboard rust?

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Joined: May 11 2007
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So, I just got my hands on a mac IIsi. I immediatley hooked everything up and tried to boot it. it powered up, but nothing happened. So I unplugged it and took the case off, and discovered rust on the motherboard, but I don't think the rust originated there. The case the power supply stuff is in had a rusty spot, and the motherboard directly under it has some rust on it. I am going to try to clean it, and I am hoping the whole thing isn't already fried. Recommendations?

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eeun's picture
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Joined: Dec 19 2003
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Re: Mac IIsi...botherboard rust?

A light scrub with vinegar and an old toothbrush or hard bristled paint brush should help remove the rust from the board.
Best to rinse with distilled water if possible, but I've never had problems with the stuff from the tap.

You might want to check for any traces on the board that have corroded under the rust.

Been through this with...IIRC it was a Quadra 700 board...and it worked fine once cleaned up. Your mileage may vary, of course.

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Joined: May 11 2007
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Re: Mac IIsi...botherboard rust?

There does appear to be some corrosion on two chips and some rust where two or three chips connect to the board. Is it dead?

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eeun's picture
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Re: Mac IIsi...botherboard rust?

Only way to tell is to clean it and see if it works!

If, in the worst case, the corrosion has eaten through a trace or the leg of a chip, you may be able to solder jumper wires across the corrosion.

If you can get the corrosion off, then you won't have to worry about shorts which could damage the board. If a trace is broken, then you won't harm it further by plugging it in.

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Joined: May 11 2007
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Re: Mac IIsi...botherboard rust?

there are a few broken legs coming off a couple chips. Sad

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Re: Mac IIsi...botherboard rust?

If you decide to scrap that machine, be sure to pull the ROM SIMM first...IIRC the ROMs from the IIsi used to go for a pretty penny as they could be used to make some earlier Macs 32-bit clean.

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Joined: Apr 9 2011
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Re: Mac IIsi...botherboard rust?

I use a butoxyethanol-based cleaner, ususally its LA's Totally Awesome Orange blah blah, and a toothbrush. Its not acidic and doesn't seem to affect any of the electronics or printing on chips. I get really nasty Apple hardware from work (a decade in the sun sometimes!) and it cleans up the hardware nicely. Now I just need to get some of the whitening gel together.

Sheet metal with rust seems to do well with Evapo-Rust, it removes the rust without any of that phosphoric acid conversion stuff that renders it paintable rather than shiny-ish again.