Re: mac quadra found

[Jason Thorpe <thorpej%me.com@localhost>]

> On Mar 22, 2024, at 7:26 AM, Jim Spath <jspath55%gmail.com@localhost> wrote:
> 
> Hello!
> While emptying a friend's house, we found a Mac Quadra (among a number
> of IBM PC clones), and I thought maybe it would run NetBSD. As the
> machine has not been plugged in for years it seems, my first thought
> was to vacuum/dust it out before applying power. After that, what
> would I look for to check if NetBSD will run?

What model is it, specifically?  I'm pretty sure NetBSD will run on all of the Quadras; they all have a 68040 of some sort with an MMU (either a full 68040, or a 68LC040, which lacked the FPU).

Macs of this era are prone to electrolytic capacitor leakage, both the surface-mount electrolytics on the main logic board as well as the bulk through-hole electrolytics in the power supply.  The ones on the MLB are the most problematic as they can damage other components or traces if they've leaked.  It is probably a good idea to closely inspect the MLB before attempting to power it on.  This may require fully extracting the board from the machine.

Even if the elctrolytics haven't spewed all over the machine, it's probably a good idea to re-cap it, as those crappy electrolytics from the 90s WILL fail at some point.  The YouTube channel "Adrian's Digital Basement" has some great videos on recapping Mac MLBs, including ones that have had electrolyte leaked all over the board.  But, while Adrian uses ceramics to replace the electrolytics (it's convenience because ceramic caps are non-polarized), be aware that ceramic caps have different characteristics and may not result in the same capacitance when used in this way.  For this reason, when I replace surface-mount electrolytics, I use new surface-mount electrolytics, not same-capacitance ceramics.

-- thorpej