HP EliteBook 8460p turn on problem

[DeniS182]

Hi,
I have problem with this laptop. After power on button is pressed laptop start and instantly goes off. When I remove main battery and CMOS battery for a while laptop starts normally and work all the day. I tried flash bios with tool from HP website and it tooks too long time approximately 6 Hours for saving old bios and 6 hours for flashing new one. Bios Is latest now. And CMOS battery has only 2.6v I replaced it.

But problem is still here.. can someone help me with this? Mobo looks fine no water damage..

Thanks

[DeniS182]

Re: HP EliteBook 8460p turn on problem

Pictures

[caspian]

Re: HP EliteBook 8460p turn on problem

Bios chip must be programmed only using a hardware-based programmer out of the laptop maiboard.
You should test the laptop in more situations. For example when the laptop works fine, check what will happen if you reinsert the two batteries and then turn the laptop off and on?
Check how long this fine working lasts if you turn the laptop off and on after a while?

[DeniS182]

Re: HP EliteBook 8460p turn on problem

I have bios programmer , but when system works I flashed it through Windows ..
Fault Is not depend on main battery.. problem Is here without main battery also. Laptop works fine/without main battery/, then I turn it off and next startup laptop post but after 1 second turn off. Then I remove bios battery for few seconds, put it back and laptop works again.

[caspian]

Re: HP EliteBook 8460p turn on problem

If you program Bios using an external programmer, you can verify whether the bios chip is defective or not.

[DeniS182]

Re: HP EliteBook 8460p turn on problem

I read bios dump by external programmer now. I upload it in right section in forum and ask someone to help me with check it or clean ME region , fix my bios file..and then I write new dump to chip and test..

[DeniS182]

Re: HP EliteBook 8460p turn on problem

I try clean ME region using Intel Easy Clean Me software. Laptop with this dump POST, but shutdown problem is still here. After 1-2 sec laptop turn off by itself.

[caspian]

Re: HP EliteBook 8460p turn on problem

Does it display anything on the screen before shutting down?

[DeniS182]

Re: HP EliteBook 8460p turn on problem

Yes, HP logo for a while and then goes off.

[nova100]

Re: HP EliteBook 8460p turn on problem

i had same proplem i solved by heating on cpu soket using bga machine and changed the cpu core caps

[mcplslg123]

Re: HP EliteBook 8460p turn on problem

It could be RTC circuit issue ,Bios issue. If you have schematic post it here.

[DeniS182]

Re: HP EliteBook 8460p turn on problem

I have this schematic

[caspian]

Re: HP EliteBook 8460p turn on problem

Now let the laptop stays in the problematic state and do not remove the CMOS battery. Then, according to Page26 of the schematics, measure all RTC-related voltages to see which one is not correct.

[DeniS182]

Re: HP EliteBook 8460p turn on problem

I measure voltages on d10 in the problem state and voltages are correct. Its there other voltages to measure? Thanks

[caspian]

Re: HP EliteBook 8460p turn on problem

If all the three pins of D10 are correct, then the RTC circuit is probably fine. Then, you should check which Bios setting leads to the unexpected shutting down. Disabling some Bios option may prevent the shut down.