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Mac IISi - is this one beyond saving?
Posted by: 8088 on 2020-12-04 00:57:56 Bought a cheap IIsI from eBay (I wondered why it was cheap!) Horrible battery bomb and corrosion. Does anyone know if there are board layouts for the PCB. I've found the schematics but some of the component references are not visible and need to replace corroded components. I've tried looking for a super hi-res pic but not having much luck. View attachment 39077 For starters looks like a lot of the pins on the CPU are eaten away so that will need replacing for sure. Need to scour the net looking for a replacement 🙁 Also the 3 xtals look like they are done for so will also need to replace those. Apart from that component wise it looks ok. Probably some smaller resistors/caps that need replacing but the pins on the other chips look ok. (Whether they work is another story) And there will be a lot of track damage. This looks like a multilayer board so won't know until I start doing continuity tests on the board. What are my chances of saving this one? Is it worth it? I've got lots of time on my hands and proficient in electronics but would like to hear some input. Am I just wasting my time? Has anyone repaired one as bad looking as this? I've got it soaking in vinegar so will see how it cleans up.
Posted by: bibilit on 2020-12-04 01:18:07 Waste of time in my opinion, found yourself another board. Better looking boards were a lost cause already for me.
Posted by: joshc on 2020-12-04 03:14:28 Agree with bibilit on this one - that board is a disaster, it would take a long time to repair, if even possible. I would look for another IIsi system to come up on eBay, they are not very rare, but a board on its own is unlikely to come up. It will be interesting to see how good it looks after a clean with vinegar though.
Posted by: 8088 on 2020-12-04 04:31:32 A few hours of cleaning with vinegar and looking a lot better but you might be right. Its still going to be a ton of work and finding spare components might be difficult CPU pins completely gone so removed it. Also 3 crytals removed as they were also rotten.
Posted by: ArmorAlley on 2020-12-04 04:46:54 Is it worth salvaging the board for the custom ICs so that they can be used on other boards?
Posted by: johnklos on 2020-12-04 07:05:11 Is it worth salvaging the board for the custom ICs so that they can be used on other boards? Certainly. Why not? But you never know - it may look worse than it really is. Sometimes it's fun to try to fix things, no matter how far gone 🙂 I had an LC II motherboard that I thought was gone because of both battery and capacitor leakage, but it's running now, and the challenge of fixing everything was fun! Now it's running Mac OS 7.6.1 and I'm testing NetBSD on it, now without problems.
Posted by: 8088 on 2020-12-04 08:40:32 If I can find the crystals and CPU I will give it a bash. Don't have much to lose. I've beeped out some of the bad looking tracks and so far so good but will need to check everything. Will be a fun project to kill some time I have over the Xmas holidays 🙂 Getting a digital scope for Xmas so will be a good project to break it in (Finally time to retire the old Tektronix)
Posted by: mattsoft on 2020-12-04 15:49:31 "He's dead, Jim."
Posted by: cheesestraws on 2020-12-05 03:05:48 But you never know - it may look worse than it really is. Sometimes it's fun to try to fix things, no matter how far gone 🙂 Will be a fun project to kill some time I have over the Xmas holidays So long as you're thinking of this as a fun project that might result in a working computer at the end but might not, why not go for it, if you'll enjoy it or find it interesting whether or not it ends up "working"? 🙂
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