On Mar 27, 9:23 am, Robert Hesson <[email protected]> wrote:
> Do all macs have this issue or is there a model line where this stopped being 
> an issue...
>
> I have a iici that's been a dhcp server since 1999 and I don't think it's 
> been opened since then. Still runs well.  I see cap issues with those once in 
> a while...
>
> I also have a quadra, a 7100/80 and an 8500/180.  Do I need to worry about 
> those as some point?

The common problem I've seen in the 7100s is that the heat sink
grease, between the heat sink and CPU, turns into dry powder and no
longer performs its function.

This leads to "mystery" lock-ups, where you just can't get the machine
to do much for very long.

I recommend cleaning off the old heat sink grease with swabs and
alcohol and replacing it with your favorite flavor of heat sink
grease.

Remember, you are only filling the imperfections between the flat heat
sink and hte flat CPU die, so do not use more than a dab of grease.
Usually the stuff is electrically conductive as well as thermally
conductive.   If you overapply and it runs onto the pins of the CPU,
it can kill the machine.  I killed a Power Computing Power 120 that
way, before I knew better.

At this point in time, I'd recommend recapping your IIci regardless.
It's just not worth risking the logic board damage.  My IIci leaked
back in 1997.  I had to replace all the caps, AND trace down an open
circuit (corroded via) and run a bypass wire from the front of the
circuit board to the back to shunt around the damaged area of the
board.

These machines were already leaking in the 90s.

The leaked goo is corrosive and very hard to see.  A casual
examination will not spot it, unless it is very recent and still
liquid.   It looks a bit like a dark dried cola stain.   Usually one
must take the logic board out of the case and hold it at an oblique
angle to a light source to visually spot the leakage, if one is not
experienced at what to look for.

These days, if I put a machine in storage, I not only pull the
battery, I desolder all the surface mount electrolytic caps as well.

Jeff Walther

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