HP EliteBook 850 G1

[joshnz]

Does not power on after shutdown.
Unless all power is removed beforehand.
Cmos battery is removed.
Battery is removed.
Power adapter is unplugged.

Once done
Insert cmos battery
Main Battery
Power Adapter at this step system will power on complain about cmos reboot and boot into windows.

If restarted will work normally.

If shutdown/powered off will not power back on. unless above steps are done.

[caspian]

Re: HP EliteBook 850 G1

have you changed any Bios option recently or updated the Bios recently?
remove the main battery and let the problem occur again. Then, check whether all voltage rails are present or not.

[SMDFlea]

Re: HP EliteBook 850 G1

Have you tested the cmos battery voltage

[joshnz]

Re: HP EliteBook 850 G1

Tried new CMOS battery.
Tried without HDD.
Updated BIOS to newest.
Tried with only power adapter.

I don't think any rails apart from cmos sram will be powered from cmos battery.
I just don't get why cmos has to be cleared for it to turn on.

unless on power off it enters some weird state.

[caspian]

Re: HP EliteBook 850 G1

It is possible that a bad Bios update has caused such a problem. Or, it is also possible that some component on the Bios circuit has got faulty. Or, it is also possible that SIO or PCH manipulates Bios content due to a faulty operation.

[mcplslg123]

Re: HP EliteBook 850 G1

If you have schematic, then look at kbc page and findout the switching pin and check whether you have 3v there. If 3v is present, try directly switching from that kbc pin by shorting it to gnd. That will rule out any bad circuit or traces in between kbc and power switch.

Btw, if schematic not avlbl, then try to findout another schematic with kbc and get the pinout from there.

[mcplslg123]

Re: HP EliteBook 850 G1

I mean another schematic with same kbc.

[joshnz]

Re: HP EliteBook 850 G1

It is possible that a bad Bios update has caused such a problem. Or, it is also possible that some component on the Bios circuit has got faulty. Or, it is also possible that SIO or PCH manipulates Bios content due to a faulty operation.

Updated bios in attempt to correct issue. old bios was from 2015.

I was initially thinking windows was putting pc in a odd power state but eliminated that theory by using shutdown feature in bios.

[joshnz]

Re: HP EliteBook 850 G1

Well i set bios to power on machine at a specific time and it did.
I found a schematic.
I have found,

Power button
Lid Switch
Power LED

All don't work.

Page 62 of HP ElitBook_840_G1_6050A2559101.pdf Is the board.

Seems like P3V3AL_PB is missing from the switch board.

The flat flex may be damaged or unplugged.

I led myself down the wrong path thinking is must be CMOS

[SMDFlea]

Re: HP EliteBook 850 G1

"I led myself down the wrong path thinking is must be CMOS"

I`ve been down that same well trodden path many times .

Thanks for the schematics

[joshnz]

Re: HP EliteBook 850 G1

found issue some minor corrosion and the cable had unplugged itself.

[ikaragozlu]

Re: HP EliteBook 850 G1

hi,
hp elitebook 850 g1
H5G42E to
CNU408B36F
I use
I have to reset the bios password
I removed the bios battery
i will be glad if you can help
Thank you in advance for your support

[joshnz]

Re: HP EliteBook 850 G1

hi,
hp elitebook 850 g1
H5G42E to
CNU408B36F
I use
I have to reset the bios password
I removed the bios battery
i will be glad if you can help
Thank you in advance for your support

What is the issue u?