[SunRescue] CPU switching

[Bjrn Ramqvist]

James Lockwood wrote:
> 
> > Speaking of soldering...
> > I have this nice SS5/110 motherboard that is broken and I was thinking,
> > is it even close to possible, by hand, to solder off the CPU?
> > I have a SS5/70 with a socketed processor and it would be happy with
> > some more horsepower. :-)
> 
> It's possible if you're careful.  You'll fry the old motherboard though.

I don't really care about that one though... perhaps you could try to
"save" a few components, if someone needs it.

> The best way of all to do it is to get one of those big screw-type chip
> pullers used for socketed PGA chips.  Clamp it to the 110MHz CPU and turn
> the handle until you are _gently_ applying force.  Then take a small
> butane pocket-torch and fan it rapidly over the back of the board behind
> the CPU.  Once the solder melts the tension on the tool will "pop" it out
> a millimeter or two, and then you can easily remove it.  The tool will
> also help keep the CPU cool as the arms that clamp onto it are usually
> aluminum.

Luckily I have such a pocket-torch at home, which I usually need when I
do some shrink-tubing on cables.
Very handy piece.

> Keep in mind that to transplant it to the new board you will not only have
> to set jumpers but also swap out the CPU clock oscillator.  Compare the
> two boards and swap the one that is different, also try to mimic the
> jumper settings.

???
And I was thinking it was just the jumpers a'la PeeCee...
(although I must keep in mind I'm NOT dealing with a PeeCee)

> Note that the probability is at least 50% that the fault in the SS5/110 is
> the CPU itself, so you might end up doing all this work for nothing.  At
> the very least, socket the oscillator so you can easily go back.

How could the CPU be fried? I mean... I've never ever experienced that a
CPU actually can die.
Is that common? Sounds very odd to me.

> Consider trying to find a Fujitsu 160MHz TurboSPARC upgrade instead.  That
> will plug directly into your socket (and you have to upgrade the boot PROM
> as well).

Are these hard to come by? Expensive? (Anyone knows where to find them?)


	/Regards, Bjorn