[SPARCbook] broken DCin connector

[Miles Nordin]

> The power jack on the back of my Sparcbook
> has broken loose on the inside.  

i had a similar problem---the center pin makes intermittent contact.
A new plug on the end of the power supply cable might have fixed it, but 
I needed a four-hour solution that worked in the Philippines, not a 
four-day solution for first-world countries, so here's what I did:

The metal connector mounting plate for all the jacks on the back, is 
ground.  You can alligator-clip the power supply's (-) lead to, say, 
the threaded nut for the /dev/bpp jack.  anywhere you like on 
the shiny metal plate.

On the external battery connector, the top pin (closest to the screen) is 
hardwired to the center (positive) pin of the DCin jack.  Using electrical 
tape artistry, you can alligator-clip the power supply's (+) lead to the 
topmost of the five brushes/pins on this connector.  You should probably 
take some pains to make sure it doesn't short out against the magnesium 
case or the neighboring brush/pin, but I haven't experienced any sparks 
or power dropouts yet.


I don't own an external battery for testing.  however...

If you open up the SB3GX so you can slide the external battery connector 
out of its slot, it's possible to manually mate it to the regular internal 
battery.  When you do this, the display will read ``Ext.Battery xx%''.  
When you execute the alligator clip trick I described above, the display 
will NOT say Ext.Battery.  This hand-waving argument suggests the top 
brush really is equivalent to the center pin of the DCin jack.

I also experimented with putting masking tape over certain pins of the 
battery pack, so onnly 4 out of 5 brushes mated properly.  I didn't do 
a good job of recording results, but I believe the following summary is 
accurate:

  o if the topmost brush is covered, the system does not receive power.
  o covering certain combinations of the center three brushes can inhibit 
    the ``Ext.Battery xx%'' display and make the system act like it's 
    connected to the DCin power supply.

Less strongly, these observations reinforce allegations that there is a 
small computer inside the battery pack which providees the two-sig-figs 
charge state information.

I know this trick isn't evecrything you dreamed of, but it did get my 
Sparcbook working again very quickly.  Yes, the internal battery still 
charges.  No, it hasn't melted after a few weeks' use.