[Repairs] XO Backlights

[Marten Vijn]

On Sat, 2008-10-18 at 13:29 -0400, Ian Daniher wrote:
> Hello All,
> I'm working on a personal project(aquarium / grow light) involving the
> LED backlights of XOs.
> If any repair center has a few extra from broken screens and don't
> plan on using them, I'd be willing to pay shipping for these parts.

I have a couple of broken screens, and be happy to send them to you.
However shipping will be more expensive than buying LED's from a
localshop. since i live in The Netherlands, Europe.

If you still want them pls, mail me offlist.

thanks,
Marten




> If you want to use them in your own project, here's what I've found:
>       * Twelve LEDs arranged as follows 
> LA1... LA4 LB1...LB4 LC1....LC4
>       * The connector has a single high(14v) line and three grounds.
>         Each ground will drive multiple LEDs evenly spaced throughout.
>         This may correlate with the above markings, but the LEDs are
>         so bright as to make it difficult to tell. 
>       * Tying together the three grounds successfully allows me to
>         drive all LEDs on the bar simultaneously. 
>       * I can drive the one positive terminal with 12v from a
>         wallwart. I've used a computer PSU with great degrees of
>         success. 
>       * The brightness of the LEDs may be controlled via PWM but is
>         definitely controlled by grounding different combinations of
>         the three ground terminals. 
>       * Reversing the voltage on the LED bar will cause between a
>         sixth and a third of the LEDs on that bar to fail, indicating
>         that, as expected, while all LEDs have very similar, they do
>         not have the same electrical characteristics.
> Best,
> -- 
> Ian Daniher
> --
> OLPC Support Volunteer
> OLPCinci Repair Center Coordinator
> --
> it.daniher at gmail.com
> Skype : it.daniher
> irc.freenode.net: Ian_Daniher
> 
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-- 
Marten Vijn
http://martenvijn.nl  
http://opencommunitycamp.org
http://wifisoft.org