Dead Hp x360 15-eb1043dx

[CraigR]

No power. I found what was a massive short under a thermocam at RT6256B 3.3 volt so I made sure no caps were shorted or anything and ordered that chip put the new one on and same thing gets hot fast. No 3.3v at the coil under it either. I have spend a very long time visually checking for any physical damage and checked just about all the caps on the whole board and mosfets. I can't record video with my thermocam but I recorded a video using alcohol. I have no idea where to go next. HELP!

[mcplslg123]

Here is the datasheet
https://www.richtek.com/assets/produ...S6256BC-03.pdf

Check Resistance to GND on pin11 and pin9(No power source attached)

[CraigR]

9.46k on pin 11 and pin 9 420k and rising.

[mcplslg123]

Are you sure you counted the pin correctly? If yes, going by your measurement there is no short on VCC as well as 3V LDO.

But since IC is still heating up,there has to be a reason.

Another reason could be short in RTC secion. check it carefully.

[CraigR]

Yes, I went according to the numbers in the pdf.

[CraigR]

I can't seem to find a thing on this. I also pulled the bios chip as a possibility and did not help. Any help would be appreciated.

[Sephir0th]

It is never the controller...

Well, at least almost never. I would proceed to measure resistance to GND of all 12 Pins, including the GND pins for a proper reference. Wouldn't be the first time that to find a short at the Enable or PGood Pin for example.

If from this still doesn't turn out anything, then the short might be hidden after a so-called load switch which gets enabled at a certain point in the power up sequence. In the moment, the switch is enabled, the controller has to push current into the short, resulting in massive heat. But of course not to measure as soon as the load switch is not enabled anymore, as in a no-power state for example.

In short: your job is to find the related load switches or to inspect every single 3.3V rail present on your board. These are usually called +3VS, +3V, +3V_WLAN, and son on so on...

[reformatt]

I've also had a shorted cap after a diode on the 3.3V LDO on a HP board once. So it doesn't register as a short directly. Schematic helps if available. Use 1v voltage injection and camera on the LDO is a start.