Apple Lisa I/O board diodes

Alexandre Souza alexandre.tabajara at
Thu Feb 18 18:57:45 CST 2016


You don't have permission to access /LisaIOBoard.jpg on this server.

2016-02-18 22:51 GMT-02:00 Adrian Graham <witchy at>:

> Hi folks,
> 'Decaying battery' panic led me to unearthing my Lisa 2/5 to check the
> state
> of the batteries on the I/O board since it hadn't been out of its box or
> powered up since 2005. Fortunately the damage is very minimal and is only
> restricted to track discolouration and external rotting of one particular
> diode which I can't find mention of on my schematics.
> Anyone with a 2/5 care to check their I/O board for me please? The diode is
> D8, just above the battery location. It's in the board in such a way as to
> make its markings pretty unreadable in the pictures I took before cleaning,
> but it's the only white diode in the machine and I'm guessing it might be a
> 5.6V 1N4734A based on what I can see. Fortunately it still works for now,
> 0.7V voltage drop.
> Pic of the board before cleaning is at
> Cheers!
> --
> Adrian/Witchy
> Binary Dinosaurs creator/curator
> - the UK's biggest private home computer
> collection?

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