At 8:46 AM -0800 11/1/99, Michael Blakeley wrote:
>As an engineer, I suspect that the heat dissipation design on the 2400/180
>isn't up to snuff, and that the repeated exposure to high temperature over
>the course of months or years eventually harms some CPU or CPU daughtercard
>components. I've seen hints of this on some Japanese sites, which seem to
>say that the problem was fixed in the 2400/240 model.
>
>If all this admitted conjecture is true, an aftermarket mod might help.
>MCE, for example, could add a head-conducting shim between the daughtercard
>and the chassis (on my unit, they aren't flush).
I forgot about that, and it is true that the heatsink pad mounted in
the bottom case half doesn't always come into good contact with the
CPU.
When I upgraded my machine to G3, I took some aluminum foil, folded
it several times into a square slightly larger than the heatsink pad,
and stuck it between the heatsink pad and the bottom case as a shim.
You have to be careful when pulling the pad up to insert the shim, as
it's easy to damage the heat pipe. Seems to work fine. Apple's
official fix was something sort of like this, a kind of flat spring
which was placed between the pad and the bottom case.
>Possibly the Newer and Vimage daughtercards include this in their design -
>but I haven't seen one. Comments from someone who has?
My Newer card didn't come with anything.
>Also, there's the issue of the backup battery. If I understand the design
>correctly, the machine won't boot with a dead backup battery. In that case,
>does the green light come on? I wouldn't think so, but if it does, then how
>can one tell the difference between a corrupt PMU state and a dead backup
>battery?
I seem to recall that PowerBooks will boot with AC power regardless
of the backup battery's condition, but I'm not sure on that.
The green light absolutely needs a power source. It's controlled
directly by the PMU so if the PMU doesn't have power it cannot turn
on. Thus, if you have a solid green light and it stays on even after
disconnecting AC and removing the main battery, the backup battery is
fine.
Tim Seufert
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