18 Sep
2006
18 Sep
'06
4:18 p.m.
Well, had a marathon evening over at Bear's place a week and a bit ago - brought over
the
disks from my ailing IRIS to see what we could scavenge. They had GL2-W2.5 on
one disk, and assorted projects on the other (looks like this was one of the machines
that
Virginia Tech had (what was it's journey over here, I wonder...) and tried to port
X11R5 to
IRIS graphics on. (doesn't seem to have worked).
Short answer - PSU seems OK, likely just noise from the improvised scope probes.
Bad news: the pin headers on these beasts seem to be getting fragile. Bear's went
out
with the same symptoms (no memory seen, no graphics) after we tried a boardswap
(to verify general functionality of a boardset, not to fix anything).
If you have one of these beasts, pull your PSU apart and replace the 4 green paper caps
on 2 boards (2 caps per board, one board is the 5v welder output, the other is the main
chopper). They seem to be on their last legs, this is the second machine I've seen
that
suffered an olfactory capacitor failure.
And the Mac stuff- IIs, IIxes and, perhaps, IIfxes have canned electrolytics on their
logic boards that leak. This effluvium has, on two occasions that I have verified, eaten
through the board trace that links the power-on circuitry to the power-on switch and
keyboard port (one II, one IIx). If you have one of these machines, you might want to
check your boards and clean them if they show signs of leakage. If you have a beast
that will not power-on, I can point you where to look... it was the same area on both
machines. No word yet if it messed with any of the other traces.