Applied fix exactly as before, but upon testing after chip installation, the machine proceeded to frag when the chip was disabled. When the chip is active no problems, chip off - FRAG.
First thought, was that the 680 ohm resistor was killing to much current and preventing the MS bios from loading. To test this theory i removed the resistor and simply bridged the 2 points with some kynar wire to restore the circuit ( sans resistor ). Unfortunately, the fragging persists. I have tested the circiut with a multimeter and it closed, therefore the wire is indeed bridging the 2 points on the track that is cut. I have gone over the MB with a fine tooth comb and can find absolutely no damage other than the cut track, which is a part of this fix. And yes, I am absolutely certain I cut the correct track.
I am at a loss to explain this. The machine behaves the way it should if that track is damaged ( fragging due to failure to load MS bios), despite the fact that it has been rebuilt. If i had inadvertantly done any other damage to the MB, I question very much that its effect would be precisely that which results from cutting that specific circuit.
I am an experienced installer, and know how to treat an exposed MB. There are no solder splashes, since the machine functions perfectly when the chip is active ( and there are no solder points anywhere near the bios chip)
The only plausible causes in my opinion are as follows. The signal coming out of the rebuilt circuit is a bit noisy and disrupting the xbox's ability to load the MS bios ( I am leaning in this direction). Or, some damage that cant be seen ( at least by my eyes ) occured to the area around the cut track, or on the opposite side of the MB from where the track was cut. In my opinion I did not cut anywhere deep enough to damage the other side of the MB, but unfortunately that is something that can neither be proven or ruled out conclusively.
I tested the rebuilt circuit without the chip installed and still experienced fragging. The bottom line is I now have a customer who will never be able to play online with his xbox, since it will never again function with the chip deactivated ( fortunately he has no plans to and was not concerned about the situation).
I, however, am very concerned. I am perfectly willing to admit when I screw up. I am also very good at dealing with anything I do screw up. In my opinion I did everything properly. In all my time installing this is the first problem caused by me I have not been able to repair. The fact is I can't repair it if I don't know what the problem actually is.
As of now I am passing on doing this fix anymore. At least until somebody can give me a plausible explanation for this behaviour. It is very hard to avoid a problem again if you cannot pinpoint its cause. And as of now there is still no real proof it is even necessary.
Any thoughts are appreciated. Keep in mind I am not an electrical engineer, so keep any explanations as dummy-proof as possible ( and forgive me if my noisy signal theory is bollocks ).
