A little help to investigate HP Probook 4730s

[pecrie]

Hi All ,

I got this laptop and the seller said that it gives no screen image.There was no power adapter with it.
I checked it and sure enough there was a dead short on some mosfets.

I replaced about 6 mosfets and it seems that the short has gone.Now when I plug in the power adapter , the white and the amber led in the power jack lit up (just for about 1 second) and then go off.

At the same time the fan spins also for about 1 second and the the white led on the power button board comes on and stays ON.

When I press the power button , 1st time nothing happens.I can press 2 or 3 times and then it seems that the system is starting.The CPU - GPU etc get warm and there is about 1.5 Amp of current.

I supect that the GPU is defective so I will need to replace it.
But the lights in the power jack must stay ON , yes ???

I have all the voltages (will check if there is 3 V at the power button).
Sometimes the system starts all by itself , so a little more work to do ...

The fan output was clogged so I guess it got too hot inside.But is that a reason to let 6 mosfets die ??

[piernov]

Re: A little help to investigate HP Probook 4730s

I have a 4750s with an issue on the white LED (flickers then go off). Replaced EC, LED transistor, power jack… didn't solve it. But that's the only issue with it, everything else works fine (including amber LED when charging) so maybe you are in a similar case and the LED issue is not important.

IIRC the board will power on by itself when attaching AC adapter after battery have been unplugged.
As for the MOSFET, would help to know which one you replaced.
Check if the BIOS POST too, caps lock LED should turn on/off when pressing caps lock key.
Check if an operating system boots too, and check on an external display.
Then you can try to flash the BIOS.

If it has an AMD GPU, it can be suspected indeed but only after you checked the above. Then you could heat up the GPU die to see if it comes up.

[pecrie]

Re: A little help to investigate HP Probook 4730s

Hi piernov ,

Thank you for a quick reply.I am wondering if the leds in the power jack must not stay ON ??

First I must say that I have the board out of the housing and have not connected anything , other than the power adapter and/or the bench power supply.And the power button

So no battery connected , thus it would be oke , if it starts on it's own , yes ??

I have replaced the mosfets : Q9315 - 9317 - 9345 -> all FMDS7692
- Q9316 - 9318 - 9346 -> all 0306AS

They are close to the CPU and the coils U9416 -9417 - 9435

Later I will connect the keyboard and see what happens

[MJ-meo-dmt]

Re: A little help to investigate HP Probook 4730s

Ahhh HP what a fun piece of shit to work on :P

Check the adapter sense/ded circuit *Carefully* the math/logic in there is fairly precise.
*would help if you have a good schematic* thats for the LED stuff...

For the no display tried another cpu? remember that its not always the GPU thats the first device choosen for display altho when its faulty it could cause some shit. iCore's have that HD graphics crap...
Checked the VGA_Core/GFX_core voltages.

HP's like to self start once you plug the adapter in, having the battery in usually solves that...

I only have a 4720s schematic (done a quick search) tho i think I got it from here somewhere...

Goodluck!

[pecrie]

Re: A little help to investigate HP Probook 4730s

MJ-meo

Yes , I understand that the CPU may have caused the 6 mosfets to go !!!
But I believe that it now is working.I have measured all the voltages and it looks if all are there.

Will measure on the CPU/GPU just to make sure.Yes , I'm looking for a good schematic for the 4730.

When I press the power button for 5 seconds the system shuts down and the white led next to the power button goes off.
So it seems to me that at least the system is operating.

For the leds in the power jack , I'm not sure how they should work.
I got the laptop as a non-functional - this is the 1st time I got up to work.

As for a new CPU , how do I know what type is in it ?The seller said that it is a 4 Gen I3 Intel.Can I then just put in another 4 th Gen I 3 ???

[SMDFlea]

Re: A little help to investigate HP Probook 4730s

Schematic for 4530s .

[pecrie]

Re: A little help to investigate HP Probook 4730s

SMDflea ,
Thank you but I also found another schematic /service manual for Probook 4730.

I'm not sure but maybe these 2 (4530 & 4730 ) are mostly the same.

[pecrie]

Re: A little help to investigate HP Probook 4730s

@piernov ,

So I did measure the voltages again on the CPU/GPU cores.And as far as I can see they look alright.

I also checked for capacitors , if they have a short.I did not find any , on the CPU /GPU core side.

So I put the mainboard a bit temporarely in the base , and I made some connections.I hooked up the screen / HD /keyboard and I also put in the battery.

Now the amber light in the power jack is flashing.This means that the battery is being charged , yes ??

As for the led on the Caps lock button.Every time when I press on the power button , the Capslock led comes ON , 1 TIME and goes off.

This is an indication , that there is an error , right ??

When the system is running , and I press the Capslock button there is NO light from the led.

For now I have left the laptop to charge the battery (to check if it will start without the adapter.

[pecrie]

Re: A little help to investigate HP Probook 4730s

Ok , so I found blog where they discussed the Capslock (and the Numlock) button led blink.With a black screen.

If the led blinks 1 time , it means that the CPU is NOT FUNCTIONAL.
I already was thinking of that , because ALL the mosfets , which provide the CPU power were dead.

So , does anyone knows , what I 3 CPU (4 th Gen ?? ) is in this laptop ??

[SMDFlea]

Re: A little help to investigate HP Probook 4730s

Hp product specs, 2nd gen i3/i5/i7 and celery B810 : https://support.hp.com/gb-en/product...ment/c02798338

[pecrie]

Re: A little help to investigate HP Probook 4730s

SMDFlea ,

Thank you.So I can put any of these CPU s in this laptop ??
Without a probelm ?? Yes ??

[SMDFlea]

Re: A little help to investigate HP Probook 4730s

Yes thats right, they`re all supported.

[pecrie]

Re: A little help to investigate HP Probook 4730s

So , then I will look for a cheap 2nd Gen CPU and then will report back.
Meanwhile I saw that the amber light is still flashing.
I don't know if the battery is charging (because the CPU is not working)

[pecrie]

Re: A little help to investigate HP Probook 4730s

Hello Guys ,

So I'm reporting about my progress on repairing this Probook 4730s.
I did manage to find a cheap 2nd Gen I 5 processor.Checked some things a little and then put on the MB.

I noticed that the amber and green light in the power jack , come on very very short.And the power button led is not ON (before it was !!)

Also the fan was not spinning now at maximum speed.Some moments it did not spin at all.And , yes , I got a picture on the screen.

I did the steps in the System Diagnostics - F1 = System ID
It passes F2 - There is a hard disk but it has no Windows (so the HD test failed)

It did say that it does not see the battery ??? But now it is charging the battery (amber led is flashing)
The DVD RW is not the right one for this laptop - so looking to buy one.

I will install Windows and then all the drivers - must download them now ...

All you guys , a big thank you for all your help and suggestions.
This was the first HP Probook and the first HP laptop , that I have repaired.

So I had to understand how things work on these models.And now I know ...

But don't worry , because I have another HP that I have to look at (so more questions will follow)

Greetzzzz ...

[pecrie]

Re: A little help to investigate HP Probook 4730s

Ok ,

So some other questions about this laptop.On Hp site it or another blog , it says that to enter the bios you should press F9.
I do get a white rectangle with the tekst " F9 BIOS options " .

But when I press Enter nothing happens.I keep seeing the System Diagnostics screen.
When I press Esc I get the " normal " start screen - with the Bios version

It has a Hard drive detected - and it says that I must install an OS on the Hard Drive.

Am I missing something here ? Still it says that there is no battery in the laptop (what does that mean ?)

The amber led keeps flashing , but after 2 hours , I can't start the laptop with only the battery inside.

[SMDFlea]

Re: A little help to investigate HP Probook 4730s

https://support.hp.com/gb-en/document/c00034791

Notebooks manufactured after mid-2011: Turn off the computer, press the power button, and then repeatedly press the Esc key until the Startup Menu opens. Press F10 to enter the BIOS Setup Utility.

Notebooks manufactured between 2008 and mid-2011: If a Compaq or HP splash screen displays after the computer starts, press Escape when prompted to enter the Startup Menu, and then press F10 to enter the BIOS Setup Utility. Some models might support pressing F10 immediately after powering on the notebook to enter the Startup Menu.

Notebooks manufactured in 2007 and earlier: Turn off the computer, press the power button, and then repeatedly press the F10 key. Normally, the Compaq or HP splash screen displays press F10 to enter the BIOS just before the BIOS menu opens.

[MJ-meo-dmt]

Re: A little help to investigate HP Probook 4730s

Glad to see it working after the CPU swap.

[pecrie]

Re: A little help to investigate HP Probook 4730s

Yes , I was happy too after all the work on it ..... )))