Jason Striegel of Hackszine writes:
Mark Hoekstra from GeekTechnique subjected his iBook’s motherboard to successive rounds of burnination and managed to correct the infamous iBook video display defect. Had this not succeeded, I think I’d still have to give him 10 points for style.
In addition to other quality control problems like frayed wires in the display hinge, a huge amount of early model iBooks suffered from a defect where the display would just completely crap out, both on the internal LCD and the external monitor output. Apple used to take these in and service them for free, but their warranty lifetime is long expired.
The problem is that the array of solder points that connect the graphics processor to the motherboard tend to fail over time. I assume this happens with the repeated expansion and contraction of components during normal use. By heating up the graphics processor with a heat gun–or, more appropriately, with a big ol’ flaming can of moonshine–you can get the solder to melt and reflow over the broken connections.
DIY obsolete iBook logic board repair – Link