HP Pavilion X360 14-dh1084tu Suspect faulty SIO

[AJ847.63e]

Hi all,

I've got a mainboard FAROE DIS X32 MB MV 18742-1 0GG03.0011.

Original state was I was getting 3v on the power button. Went through the schematic power sequence and we seem to be getting stuck at point -4. The outputs from the SIO 5V_S5_EN and S5_EN are missing, and the inputs for PU4551 seem wrong. 1.36V and 9.6V for En1 and EN2 respectively. At first I was getting 3.34V on EN1 but it's seemed to have dropped. PWR_5V_FB is 0.6V.

Checked all around the board can't see any shorts, except around the dimm slots and CPU so I'm assuming that's normal. 180 ohm or so on DDR rails or 1.2 power rails. Checked all the caps around the SIO nothing is shorted but thermal imaging reveals the SIO slightly heating up in the center only, gets up to about 27C. So I wanted to seek some recommendations on whether that seems normal, or considering the heat and the outputs missing, the SIO is likely faulty. Again, for confirmation all -5 step rails are present and correct, so it seems like the SIO is getting powered and being told to turn on but it's not outputting anything.

Thanks for the assistance.

[SMDFlea]

Post a link to the schematic,do not attach it to your post please. https://www.badcaps.net/forum/troubl...f-this-section

[AJ847.63e]

It's a paid forum hence why I didn't link to it.

[reformatt]

The 3V LDO (3D3V_AUX_S5) that feeds the EC is only rated to 100ma. It would current limit and you'd see this voltage lower if there was an abnormality within the EC.

Check that you have 3D3V_AUX_S5 to all pins that need it on the EC, along with any other pre-requisites (RESET is high etc). Check if you can dump the EC firmware with a SVOD etc.

[mcplslg123]

PR4508 & PR4509 gets corroded on this board-has faced this issue 3-4 times They act as voltage divider for pin11(EN2) of PU4501.

Both the resistors are located on the opposite side of PU4501.

The boardview is posted in this forum. Use forum search.

[AJ847.63e]

Thanks for the assistance. I Think the cpu on this thing is dead unfortunately. I hooked the board up again to my dc supply this morning and now it’s pulling .067A when it originally was at .016/17 and dipped down to .007 briefly.

I checked voltages and again we’re still stuck at step -4 and EC outputs are missing. Though strangely VCCSA is present 1v and if I take the cpu heatsink off you can see a very distinct hotspot the second you turn the power supply on than it shuts off and after 40 seconds heats back up and stays up.

I’ll recheck the reset line and 3D3V_AUX_S5 ( only checked it at the one spot originally) and check those resistors on Monday and report back but it doesn’t look good. Should VCCSA be up this early in the boot sequence? Tried to find it in the power sequence diagram but didn’t see it. I thought system agent is for powering the internal IO subsystem of the cpu like the ring bus and IMC?

thanks again for the assistance.

[reformatt]

1V_VCCSA implies that ALL_SYS_PWRGD is ok. That means you have all your rails up to S0. So what you're describing isn't logical as you said not even S5 rails were being enabled.

[AJ847.63e]

Both PR4508&9 are reading as per the schematic. Turns out there was a tiny piece of metal in between pins 115 and 116 on the SIO so I guess that was why VCCSA was up. Very strange as VCCSA was up when I first got the board and before I removed it from the chassis, as soon as I took it out of the chassis it disappeared for quite a while before coming back a few days later. Now the boards back to drawing 0.017A and briefly dips down to 0.007A every few seconds. Both -4 rails are up as is PM_PWRBTN#. Everything seems to be working up to stage 0 RSMRST#_KBC. AC_IN# and PM_SLP_S4 are missing and not STG.

[AJ847.63e]

Should clarify everything is up before RSMRST#_KBC, RSMRST is 0V and not STG. I've confirmed 3V3 is present on all of it's pins on the SMC, as is AC IN and KBC_PWRBTN#. PM_SLP_SUS# is present but S4 is missing. PU4501 see,s fine, removed both the mentioned resistors and they measured as per the schematic. 9.64v en2 @ PR4509 & 3.34 FOR EN1 @ PR4515.