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Elfen

Mac IIsi Recap Success

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It's Alive! Well, not exactly, but it was successful.

 

Washed the board, dried it with my heated air pencil, and did each capacitor one at a time. GOD WHAT A HEADACHE!  Took 2 hours! But in checking and rechecking, I found no rotted traces. NONE! What Luck! I did find that several caps were glued to the board, making the cap removal that much more harder.

 

But there was a problem - the black caps I use were slightly larger than the space the old caps allowed! So there was some trouble soldering each cap, so after each cap, I checked each one with a multimeter to make sure it connected to the board, the joints and the traces.

 

This particular IIsi has a dead PSU, this I know and it needs a recap as well (perhaps one day!). But the other IIsi I have has a questionable PSU. In swapping them for a test - the board turned on, audio works, issues with the VGA monitor resolution occurred but that was expected. Also - the original RAM in the machine is dead, giving the Chimes of Death. But swapping out with working RAM I know - the IIsi turns on and boots! Mouse works, keyboard works too!

 

But again, this second PSU is iffy, and after it warmed up, problems came up. Sudden Shut Downs, sudden restarts, boot freezes. etc. Let it cool, and works fine until it gets warm.

 

So congrats to me! Looks like I got the curse broken. The other IIsi will get a recap tomorrow or during the weekend. It depends on how I feel after I get my second radiation treatment early tomorrow. Just got to figure out how to open the PSU. It looks what a tin can of food would look like to a cave man armed with a rock.

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Thanks for posting.  If I had found the caps being too big, I probably would have been scared away!  odly enough the Two IIsi machines I've owned had been the most badly treated by previous owners yet work fine.

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Before attacking the PSUs, check the threads here about re-capping IIsi PSU.   There are lists of cap values and other hints from experience. Note specially that the small sub-board containing the start-up circuit in the PSU is often the main, sometimes only, cause of failure.

 

Rick

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Thanks RickNel. I am aware of the PSU idiosyncrasies. It is not just with Cap Values, but also their physical measurements. I recapped an LC Supply once with the same value caps but the physical size differed, so the recapping job became a job and a half of making things fit inside that small case. Eventually I got it together and it works great. CompuNerd went through the same issue as well when he recapped an LC Supply. So it is not only the µf values but also the physical size as well.

 

Just like in this case - the Tantalum caps I used on these IIsi boards (which I recapped other Mac boards with no problems) were bigger than the physical space the old caps were in. So it took some doing to get them in.

Edited by Elfen

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Thanks for posting.  If I had found the caps being too big, I probably would have been scared away!  odly enough the Two IIsi machines I've owned had been the most badly treated by previous owners yet work fine.

 

Capt'n, I'm thinking that the next time I run into this problem again, I'm getting a bunch of smaller sized ceramic SMD/SMT caps for those boards. They are just as good as Tantalums from what I hear but I use the black Tantalums because of appearance - they look like they belong there. And Ceramics are cheaper than Tantalums.

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