Hello community,
This will be the device of your nightmares. I can't count how many hours I spend to fix it, but it was already way to much...
However, I really hope for some insight from experience because I have this nice HP ZBook 15v G5 here which came in completely dead, even +VREG3 not working although it wasn't shorted. Previous repair attempt by a somehow professional repair shop, since I noticed action around the controller responsible for +3VALW and +VREG3 without it making worse. Way later I noticed the PCH was replaced and even later I realized +3VALW was shorted with +VCC_RTC through shorted solder balls underneath the PCH resulting in voltage "bleeding" from +VREG3 even into +3VALW.
Long story short: I have replaced the PCH again and the short between the power rails went away. Unfortunately it still didn't really powered on, just a small try, 3V and 5V Alw coil present for a short while, then dead, no response from power button because it wasn't even 3.3V on it.
However, actually I did found even two workarounds to power it on, full post, and loading Windows.
1. Injecting voltage into the ON/OFF# rail responsible for the power button
2. Removing the PD-Controller, a TPS65987SCE. It is even enough to cut the +VREG3 from this controller to get the board working and let it respond to the power button.
However there are issues left when I apply the workarounds:
- USB-C not working at all
- a exclamation mark in Windows Device Manager, talking about "UCM-UCSI ACPI DEVICE" with Error 43
- it does need very long to boot/to show picture. At least 30-40 seconds when it is connected to the charger/battery and even minutes when where was removed all power before.
What I did in addition was to rule out a firmware issue by messing with the HP files and sourcing the TBT firmware dump and of course to reprogram it with external prigrammer. Also I have replaced the TPS65987SCE and reballed the Thunderbolt Controller, a JHL6340, without any progress. It doesn't even boot without the TBT Controller present.
I do not share any measurements or pictures at this point since there exists even hundreds. Some maybe related, some maybe not. What I can say is, I checked the suspects in detail and I didn't found anything obvious around the TPS65987SCE and the JHL6340 regarding voltages and resistances. So just ask if something would be important to know and I'll share.
At this point I have only one hope left, to replace the JHL6340, but I'm of course open for any suggestion.
Thanks in advance.
This will be the device of your nightmares. I can't count how many hours I spend to fix it, but it was already way to much...
However, I really hope for some insight from experience because I have this nice HP ZBook 15v G5 here which came in completely dead, even +VREG3 not working although it wasn't shorted. Previous repair attempt by a somehow professional repair shop, since I noticed action around the controller responsible for +3VALW and +VREG3 without it making worse. Way later I noticed the PCH was replaced and even later I realized +3VALW was shorted with +VCC_RTC through shorted solder balls underneath the PCH resulting in voltage "bleeding" from +VREG3 even into +3VALW.
Long story short: I have replaced the PCH again and the short between the power rails went away. Unfortunately it still didn't really powered on, just a small try, 3V and 5V Alw coil present for a short while, then dead, no response from power button because it wasn't even 3.3V on it.
However, actually I did found even two workarounds to power it on, full post, and loading Windows.
1. Injecting voltage into the ON/OFF# rail responsible for the power button
2. Removing the PD-Controller, a TPS65987SCE. It is even enough to cut the +VREG3 from this controller to get the board working and let it respond to the power button.
However there are issues left when I apply the workarounds:
- USB-C not working at all
- a exclamation mark in Windows Device Manager, talking about "UCM-UCSI ACPI DEVICE" with Error 43
- it does need very long to boot/to show picture. At least 30-40 seconds when it is connected to the charger/battery and even minutes when where was removed all power before.
What I did in addition was to rule out a firmware issue by messing with the HP files and sourcing the TBT firmware dump and of course to reprogram it with external prigrammer. Also I have replaced the TPS65987SCE and reballed the Thunderbolt Controller, a JHL6340, without any progress. It doesn't even boot without the TBT Controller present.
I do not share any measurements or pictures at this point since there exists even hundreds. Some maybe related, some maybe not. What I can say is, I checked the suspects in detail and I didn't found anything obvious around the TPS65987SCE and the JHL6340 regarding voltages and resistances. So just ask if something would be important to know and I'll share.
At this point I have only one hope left, to replace the JHL6340, but I'm of course open for any suggestion.
Thanks in advance.
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