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The HP ProBook line of business laptops was released in April 2009, aiming to be a lower cost to HP's EliteBook lineup.

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Display, mouse and keyboard stopped working

Hi,

I bought a new battery to replace the dead one I had. I installed it and the computer worked fine for 1 minute, then the display disapeared.

The battery is working fine.

I connected an external monitor and saw that the mouse and keyboard stopped working too. They don’t work in the bios either.

I didn’t have to open the computer to change the battery so I dont think I messed up something physically.

Any ideas on how to fix this are welcome

Answer this question I have this problem too

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What happens if you take the battery out and just power up with the charger?

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The computer boots, but without display, keyboard and mouse. But external devices work

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what if you plug in a external keyboard and mouse?

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@alex955

What is the model number of the laptop as shown on the information label on the bottom?

You said that "They don’t work in the bios either" so does this mean that there is a display when in BIOS?

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I connected external display, mouse and keyboard. They all work and the computer works, it's just the internal display, mouse and keyboard that are not working anymore.

@jayeff, I'm not home right now, I'll check tonight but the model is 6460b. I don't know if there is soming more precise

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Hi @alex955 ,

The following is just trying to isolate what the problem may be as it seems that with multiple failures there should be a common factor and the only common factor I can think of at the moment is a power supply problem to the affected components.

The keyboard and touchpad are both handled by the keyboard controller which interfaces them to the motherboard chipset (southbridge) whereas the LCD panel is connected directly to the northbridge chipset. this chip also handles the display to the external screen so presumably it is OK

Try shining a torch at an angle close to the laptop screen to check if there are any images being displayed after the laptop has booted. They will be very faint if they are there at all, so trying this in a darkened room may help to see them. If they are there then there is a backlight problem i.e. power problem

You could also try a power refresh in case it is a corrupted BIOS.

Here’s the maintenance and service guide for the laptop. Go to p.116 to view the necessary pre-requisite steps and then the procedure to remove the systemboard.

This is just to gain access to the board and not to remove it.

The power refresh involves the following:

Turnoff the laptop and disconnect the charger if connected.

Remove the main battery.

Disassemble the laptop to access the motherboard and then remove the coin cell RTC battery from the motherboard. Note the orientation of the battery before removal. Usually it is +ve on top as marked on the battery.

Press and hold the laptop Power button for a full 30 seconds and then release it.

Reverse the above procedure and then try starting the laptop and check what happens with the display.

If still no good then the voltages on the motherboard need to be checked. Here’s the motherboard schematics that will help with this.

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Hello, thanks for this answer. I'll check that tomorrow and return with what happened !

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I juste tried your procedure with no success... Could you indicate which voltages need to be checked please ?

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@alex955

I can't find any common voltage between the LCD screen and the keyboard controller that doesn't also affect other components e.g. USB which are working.

The best then that I can suggest is to test each failure as a separate issue.

See p.37 of the schematic.

On the LVDS cable connector, pins 1, 2, 3, 5, 7, 9, 11 &12 there are 4 different power supplies connected +v3s,+vbatr, +lcdvdd & +v5s.

I suggest that you test the voltages at the components where the voltages appear rather than the cable connector as there are earths close by and it would be easy to short out the power by bridging the test probe across two pins when you shouldn't i.e test at C6102, C6103, C6104, C6106 & R7037

With the keyboard controller chip (KBC) it is +3VAL but as I said other functions work and this chip controls them as well. so I don't think that no voltage is a problem for it.

It may be a @aactech said software but I don't know if reloading the BIOS would work as a reset didn't. Perhaps it is the chipset software

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How should I proceed to reload the BIOS ?. I've also read that the CMOS battery could be the cause of the trouble. Seen the cheap price, I've ordered a new one

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@alex955

Removing the RTC (Real Time Clock) battery (aka CMOS battery) and the main battery should have reset the BIOS back to factory default.

The RTC battery is there to maintain the BIOS settings when the laptop is turned off.

If the battery was faulty then after the 1st "reset" the laptop should have worked but perhaps it may have failed again the 2nd time that the laptop was started after having been switched off.

As to reloading the BIOS, search online for "Probook 6460b bin bios file" to find the download and hopefully instructions.

Be aware that it has to match your EXACT motherboard model and version number as there are several different motherboards used for the Probook series

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I turned the computer on and I was busy on another computer when… The display, the trackpad and the keyboard started working again, just like that, poof.

I really don’t understand what happened…

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I suggest corrupted drivers. Windows does have some limited capability to repair itself. So that is why things can appear to "magically" work after a number of shutdowns and startups over a period of time.

Apparently drivers work at a number of levels so sometimes not so obvious.

Graphics being the most complicated and this relates of course to displays.

I have been where you have been so......many times over the last 35 years.

Troubleshooting requires good methodical process - meaning do each step very carefully but then sometime an intuition will arise and fixed.

Happy for you. This was quite epic. @jayeff always has good knowledge and ideas.

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Not so fast... They stopped working again a few hours later

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@aactech I've updated all the drivers, and still no keyboard, trackpad or display

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@alex955 Did you update the BIOS from the HP site?

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@aactech Yes, with their utility software

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Alex will be eternally grateful.
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