Hey,
I've gotten fairly far into this diagnostic but I thought I'd get some input (no pun intended). We had an ASUS X200CA brought in not powering or showing any signs of life. No luck with power flush so I tore it apart to get the board. Found the motherboard schematic (ASUS doesn't like numbering their boards with anything besides the laptop model but they also seem to re-use boards in different models) and essentially just followed power all the way from the 19v DC jack to a step-down switch mode power supply IC chip.
Datasheet for the chip says it takes the input and switches it to a 3v and 5v output with PWM buck converters as well as handles onboard power-up sequencing, a power good output, internal soft-start, and a soft discharge output that prevents negative voltage during shutdown. Made sense this would most likely be the issue so I tracked down where it was on the board and it was a little gunky around the area.
Took the chip off, cleaned both it and the board with rubbing alcohol, put it back on, and viola it powered up. My excitement was short lived though as it powered down 30 seconds later. The same thing happens each time I turn it on. Shows the red charging LED, it powers up when I press the power button, and then clicks off entirely shortly after.
My initial thought is to just replace this IC chip, but part of me is second guessing that's the only issue. Any of y'all ever experienced this before? Any thoughts on if something else could be contributing or should I just go ahead and order the chip and see if it works when it comes in. I've attached the board schematic I'm using as well as the datasheet for the IC in question, Page 79 on the schematic is where the chip is mentioned with the ID PU8701A
Thanks,
Brandon
I've gotten fairly far into this diagnostic but I thought I'd get some input (no pun intended). We had an ASUS X200CA brought in not powering or showing any signs of life. No luck with power flush so I tore it apart to get the board. Found the motherboard schematic (ASUS doesn't like numbering their boards with anything besides the laptop model but they also seem to re-use boards in different models) and essentially just followed power all the way from the 19v DC jack to a step-down switch mode power supply IC chip.
Datasheet for the chip says it takes the input and switches it to a 3v and 5v output with PWM buck converters as well as handles onboard power-up sequencing, a power good output, internal soft-start, and a soft discharge output that prevents negative voltage during shutdown. Made sense this would most likely be the issue so I tracked down where it was on the board and it was a little gunky around the area.
Took the chip off, cleaned both it and the board with rubbing alcohol, put it back on, and viola it powered up. My excitement was short lived though as it powered down 30 seconds later. The same thing happens each time I turn it on. Shows the red charging LED, it powers up when I press the power button, and then clicks off entirely shortly after.
My initial thought is to just replace this IC chip, but part of me is second guessing that's the only issue. Any of y'all ever experienced this before? Any thoughts on if something else could be contributing or should I just go ahead and order the chip and see if it works when it comes in. I've attached the board schematic I'm using as well as the datasheet for the IC in question, Page 79 on the schematic is where the chip is mentioned with the ID PU8701A
Thanks,
Brandon
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