Fix clock instructions updated

[Paul Fox]

daniel wrote:
 > Having seen a handful of RTC battery problems in Nicaragua I found
 > myself revisiting the process, and struggling to explain the wiki page
 > to the team.
 > 
 > So I restructured it a bit, mainly to take the focus away from the
 > problems caused by ancient firmware versions and badly shaped holders,
 > and instead to focus on the problems caused by battery leakage and
 > defunct batteries (the common cases nowadays).
 > 
 > I also added some information about the XO-1.5 with help from Paul
 > 
 > http://wiki.laptop.org/go/Fix_Clock
 > 
 > Review appreciated..and one detail we're not 100% sure on: does the
 > XO-1.5 continue to use exactly the same RTC battery as the XO-1?

yes, the coin cell itself is identical:  ML1220

however, as you've noted, the XO-1.5 version has wire tails on
it, which lead to the new connector.  the wire tails are attached
to legs on the battery which are spot-welded in place during
fabrication.  soldering to a coin cell battery case is not only
difficult, but potentially dangerous -- they can (literally)
explode.

we'll have to see about making "leggy" versions of the battery
available (though hopefully they won't be needed right away).  in
the meantime, the wiki page should suggest searching for "ml1220
legs" or "ml1220 pins".

here's an example of a suitable replacement:
    http://www.pchub.com/uph/laptop/602-25682-4052/Sanyo-ML1220-Battery-Coin-Rechargeable.html

paul
=---------------------
 paul fox, pgf at laptop.org