I got a huawei D15 that came in for no power repair. Device charges , charging led flashedms but doesn't turn on. I found corrosion on an IC (ic name is BDJCY1...I can't find out much info about it online). I removed this ic and two pads are corroded but they can be repaired. To my knowledge inductors never short to ground (i might be wrong and please those that are more knowledgeable than me can correct me). I found few inductors short to ground when my multimeter is in beep mode ,indicating a short in the line of those inductors...but I don't know how to go about to find the shorted component on this D15 board because I don't have the schematic or boardview to see the components that might be connected to the shorted line. The red arrows show where the multimeter is beeping and the yellow arrow shows the component i found corroded
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You are correct, inductors usually do not short to ground. But the semiconductor bevore it and the semiconductor after it can make a short.
As from your photograph, the 5V, 3.3V, 0,75V and 1,1V rails have a short.
So, please measure now the ohm resistance to GND. A resistance lower than 2 or 3 Ohm, I would consider a "dead-short". A slightly higher resistance will keep the multimeter beeping, but it's not a real dead-short.
If you can use a proper power supply, you can use let's say 0,5V and some current and digger out whether there is really a dead-short. A real dead-short will be always there, even with less voltage.
Keep significant distance to the 0,75V rail, us 0,5V or less.
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Originally posted by FriedFred View PostYou are correct, inductors usually do not short to ground. But the semiconductor bevore it and the semiconductor after it can make a short.
As from your photograph, the 5V, 3.3V, 0,75V and 1,1V rails have a short.
So, please measure now the ohm resistance to GND. A resistance lower than 2 or 3 Ohm, I would consider a "dead-short". A slightly higher resistance will keep the multimeter beeping, but it's not a real dead-short.
If you can use a proper power supply, you can use let's say 0,5V and some current and digger out whether there is really a dead-short. A real dead-short will be always there, even with less voltage.
Keep significant distance to the 0,75V rail, us 0,5V or less.
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The 0,5V you can inject everywhere on the board. Even in the delicate area of the CPU and GPU, those chips use 0.65V and higher. With a voltage of 0.5V usually can flow a current only on dead-shorts. silicon semiconductors start conducting at 0.6V.
If you have found a dead-short, but it doesn't shine-up in the thermal camera image, you can raise the voltage up. Usually the voltage sinks down to 0.1V or so, but the current is still flowing. This is a sign for a dead-short. While current is flowing, you can raise the voltage a bit, until you can see the shorting component in the thermal camera image. It's also possible to touch the surface of the board and "detect" the heat dissipating component with your hands.
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