I bought a broken 1.33 GHz iBook off eBay and it ended up being a 1.2GHz (totally different logicboard), I kept it, pretty confident I could fix it. I would test it with the shim repair on the power regulator vReg thinky. No joy. Then shim the video chip. Nada! I thought maybe if the external video was not affected it could simply be a video cable. Bought an external VGA adapter and tried it. External still has the same problem. Phooey!
It doesn't have the 'black screen' but it has the 'rainbow screen' so I don't think it is the vReg chip. It is actually somewhat usable though if you use it a while the distortion gets worse to the point of un-usableness. With this problem I think it is best to assume that it is the video chip connections themselves that are the problem. After partly disassembling the iBook I started it up and pressed on the video chip, no change (which I figured as the shim did no good either.)
I fearlessly decided to use the 'coin' method of heating the chip up to reattach the BGA chip to the board. I then pondered over the dissected iBook next to my Pismo here for at least a month... I scared up the courage to use two pieces of 1/2" x 1/16" brass instead of a British 2 pound piece or a US 50 cent piece. I heated them up to 475 degrees (!) for 15 minutes for good measure and set them on the chip with pliers. STILL NOTHING!!! OK. Hold on now. The brass may have been a little small.
That was two weeks ago. Tonight as I type this I have heated a piece of 1 1/4" x 1/8" bar iron in the oven and placed it on the chip. No smoking or hissing... Now it is cool and the iron has been removed. Now the moment of truth: To partly reassemble and test for a clear screen, here we go...
Pfffffft! No change. Screen is still a mess. I really don't think the 'coin' method produced enough heat to melt anything. After about a minute I was able to touch the metal with a wet finger, it felt hot and the moisture evaporated but I don't think it was enough to really do anything.
I think it really needs the heat gun to get it hot enough. Its either do that or send it back to ebay as is and see if I can get my $120 back.
Any ideas from you o so experienced ones?
Tried it again at 525 degrees. No improvement.
I tried this method, and had moderate success heating piece of copper directly on the video chip. I used a heat gun on low setting, and placed a bead of solder on top of the copper block. When the solder melted, I backed off the heat, thinking that the copper was now transfering enough heat through the video chip to the BGA.
I did see some improvement after trying this a couple times. I went from nothing to about a 15 minute uptime before seeing problems. Twisting the case helped, but I figured I'd try again.
Unfortunately for me, I applied more heat this time, and not thinking about the weight of the copper block I was using, it melted too much of the BGA and the video chip basically sank onto the motherboard, turning the BGA into an LOS (lump of solder):P
You should not have that problem heating a few coins directly on the chip if you're careful.