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Hi. I have board 820-2915-b and when i open it D6990 and R6990 was burned out. i replaced U6990, R6990, D6990 but now when i connect charger smoke coming out from R6990. Also i have short on U6990 pin 4 and pin 7. Anybody can help?
Look at the diagram. What besides U6990 has a path to ground on U6990's pins 4/7? C6990! C6990 has one pin on ground, and the other pin on U6990 pins 4/7. C6990 is the only other path to ground here, so replace and fix. R6990 acts as a fuse and will blow if something is shorted to ground in front of it.
i think we will not gona fix it. there is burn hole in board and can be shorted to layer bellow. i removed u6990, c6990, r6995, d6990 and i still have short on pin 4,7 on u6990 and c6990. i think it will go to scrap. but thanks any way for trying to help
That is why you bypass the board. Only a few components on this rail so easy to construct with some wires. You could also cut out the area of a dead board and wire it into this board. Many possibilities to fix this board, in no way is this board trash.