Unable to Locate Power Supply Chip on HP Elitebook 840 G3

[Zentech]

Has Anyone Unlock HP Elitebook 840 Successfully

Since I unlocked an HP Elitebook 840 G3 which I bought on ebay, the laptop is behaving weird. I dumped the original bios file back into the bios, but now is not booting to bios screen. I have the 19V led on, and power button led also on, I have 3, and 5V, but when I press the power button nothing happens. I notice I have 2.3V on power button. That seems also weird since it should be 3.3V. I press power button and it goes to 0V but board does not come on. After I unlocked the bios, the board came on and I was able to get into the bios no problem. after booting like three times, it started shutting down and restarting by itself. I notice that one of the pads under wson bios was damaged so I change to the bios to soic8 and dump the file. got my voltages back. but continue to power on and off. But no video!...
has anyone here has successfully unlock HP Elitebook 840 bios and laptop worked find after that?
thanks

[Zentech]

Re: Unable to Locate Power Supply Chip on HP Elitebook 840 G3

It's actually much easier to solder than to use pogopins. And no, these boards are far from delicate. I guess you probably just tried to yank it off before it was ready. When heating, just use tweezers to slightly push the chip sideways once in a while. When it's ready, it moves. At that point, grab the chip.

ok... I manage to dump the bios file into a winbond 25Q128FV bios, solder on the board now I got power. 19V led comes on the fan comes on, the 12V for the charger are present; however, when pressing the power button boards does not come on. I don't get anything on the screen.
I took a pic of how the pads for bios connection are after I switch to isoc8 type of bios. How can I know if the pads are making a good connection and the pads on the board are not bad? check out the pics attached

[RethoricalCheese]

Re: Unable to Locate Power Supply Chip on HP Elitebook 840 G3

It's actually much easier to solder than to use pogopins. And no, these boards are far from delicate. I guess you probably just tried to yank it off before it was ready. When heating, just use tweezers to slightly push the chip sideways once in a while. When it's ready, it moves. At that point, grab the chip.

[Zentech]

Re: Unable to Locate Power Supply Chip on HP Elitebook 840 G3

Soic you mean. Yes, just write the wson content to Soic and solder it to those gold pads.

is there a clip out there for programming the bios on board, without removing it. this boards are so delicate that you risk damaging the rails. I have one but is a pain in the butt to get it to work.
https://www.amazon.com/AiTrip-EEPROM.../dp/B07V6WLF4S
is there something like a pogo click that sits on top of the chip? If anyone can provide link.. much appreciated

[RethoricalCheese]

Re: Unable to Locate Power Supply Chip on HP Elitebook 840 G3

Soic you mean. Yes, just write the wson content to Soic and solder it to those gold pads.

[Zentech]

Re: Unable to Locate Power Supply Chip on HP Elitebook 840 G3

ok. I desolder the BIOS chip and noticed that the contact under the chip (wson pin layout) was damaged during the initial unlocking of the bios. It seemed ok when I solder it back. Is there a way to convert the pin layout of the motherboard bios from wson to isoc and use an equibalent isoc bios chip with same storage? can I just use an isoc type of bios dump the bios file and solder on the board?

[mon2]

Re: Unable to Locate Power Supply Chip on HP Elitebook 840 G3

@Zentech,

you are referencing the Richtek charger ICs. They do offer a mix of parts where the +3v3 & +5V0 rails are ALW (always ON) or another version of the same charger IC which will turn ON these same rails via a logic level asserted onto the ENABLE pin.

The versions of the Richtek parts (with and without the ENABLE for the +3v3 & +5v0 LDO rails) are selected by the suffix of the part number. From memory believe that "A/B" versions are ALW where "C" suffix is with an ENABLE pin.

On this TI part, do not see the always on rails.

[Zentech]

Re: Unable to Locate Power Supply Chip on HP Elitebook 840 G3

bq24780s. awful picture but very readable

thanks buddy.. I though it was 747805..
One thing I'm confuse with this board is that in past boards, the charger ic, also provides 3, 5V PVC (REGV) so as soon as you plug in the charger, the ic VREG pin gives you 3, 5V to power on the board. Not in this case... apparently the 3, 5V power supply is separate. How do you find that ic without schematic? VREG is not 3VALW which you can measure at the coil and it is present once the I/O IC starts the board. Some boards are different than other in that sense. How they provide 3.3V and 5V at charger connect (which is not the same as 3, 5VALW)
correct me if I'm wrong
thanks

[RethoricalCheese]

Re: Unable to Locate Power Supply Chip on HP Elitebook 840 G3

bq24780s. awful picture but very readable

[mon2]

Re: Unable to Locate Power Supply Chip on HP Elitebook 840 G3

That is a very poor quality picture.

Can you pour a bit of alcohol on the top of this IC and use a bright light to read off the laser markings on this device ?

Post all markings on this device, line for line.

2nd line appears to be BQ78 = Texas Instruments but that is not confirmed.

[Zentech]

charger IC For HP Elitebook 840 G3

guys, I need to the serial number on an chip on my motherboard. don't have the schematic and chip serial number seems worn out. This is for HP Elitebook 840 G3
Motherboard S/N 6050A2822301-MB-A01
I manage to get the schematic for previous version of laptop, but numbers don't match on the board.
it is U6000, which is near the charger. I took a picture to search for the chip data sheet, but it is not possible to see clearly.

[Zentech]

Re: Unable to Locate Power Supply Chip on HP Elitebook 840 G3

I don't see a light when charger is connected. Here are more pictures requested of power supply L6000 (both sides)

[SMDFlea]

Re: Unable to Locate Power Supply Chip on HP Elitebook 840 G3

what attitude?... you just join the forum on 2020. are you looking for newbies to bash?

To be fair he did ask you at post #9 for more pictures.Lets not forget,its you who has the board in front of you.If you don`t want to post more pictures thats fine.

[Zentech]

Re: Unable to Locate Power Supply Chip on HP Elitebook 840 G3

So you're expecting further Help with this Attitude? Then i have to disappoint you. Without me.

Good luck for solving the issue!

what attitude?... you just join the forum on 2020. are you looking for newbies to bash?

[SMDFlea]

Re: Unable to Locate Power Supply Chip on HP Elitebook 840 G3

Are you using a genuine hp charger.Does the white light come on at the power jack.Have you tried different ram.Have you tested the DC-IN mosfets. Have you found the charger IC and taken voltage and resistance measurements.Have you tried flashing the bios.
Have you made a list of all the voltage regulators you can find on the board,and found schematics and datasheets for those. Is the charger IC and any of the voltage regs the same as in the 840 G2 schematic

[Sephir0th]

Re: Unable to Locate Power Supply Chip on HP Elitebook 840 G3

So you're expecting further Help with this Attitude? Then i have to disappoint you. Without me.

Good luck for solving the issue!

[Zentech]

Re: Unable to Locate Power Supply Chip on HP Elitebook 840 G3

I think we can't continue Like this. I even can't find the Coil L60000 on your Pics, which you mentioned before Just for example.
If there are No Schematics available we need CLEAR Pics of both sides of the whole Board (No zoomed in Pictures). Give the coils Numbers starting from Zero and write them near the coils or write the measured values directly near corresponding coils.
When a suspicious area is found we can continue with zoomed in Pics, but Not yet.

the voltage value for every coil / power supply are above along with their resistance. I also posted pictures. If you zoom in into the pics you can clearly see the coils and numbers. All those voltages are S5 stage (power off with charger connected). L6000 is the first power supply close to the charger. I don't think is for 19V or even if it is suppose to have any voltage at S5 (power off) Because even if it getting 19V on drain, is not going to conduct to source if not polarized on gate (so it is important to know which power supply is providing what voltage and when is it suppose to come on)

[Sephir0th]

Re: Unable to Locate Power Supply Chip on HP Elitebook 840 G3

I think we can't continue Like this. I even can't find the Coil L60000 on your Pics, which you mentioned before Just for example.
If there are No Schematics available we need CLEAR Pics of both sides of the whole Board (No zoomed in Pictures). Give the coils Numbers starting from Zero and write them near the coils or write the measured values directly near corresponding coils.
When a suspicious area is found we can continue with zoomed in Pics, but Not yet.

[Zentech]

Re: Unable to Locate Power Supply Chip on HP Elitebook 840 G3

Yes, close enough to zero ohms to consider it a short. Do note that some low voltage rails are fine to have a low resistance reading. That is normal for cases like 0v8, 1v0, etc.



I would start with this coil as the power rail appears to want to power up but is shutting down to some local event. Review the nearby mosfets and read off their markings. There should be 2 mosfets that will look similar - one for the high side / another for the low side for this switching power supply.

Also any nearby local IC that is likely to be the switching buck converter for that rail. What are the markings of the local IC near L60000? Maybe with enough info, we can locate a common schematic that will show us on how that IC should be wired up for a deeper investigation.

With the resistance reading of 40k ohms on this coil / power rail - the rail is not shorted. This is a good sign.

ok. I made a video, which I think is easier for you to see what I'm doing.
I was able to trace 19V to Q6000 which part of the same Power Supply as L6000. I have 19V coming in but no voltage on gate and of course no voltage on source which I believe is connected to the other mosfet Q60001.
what should I do next? should I check the driver for this mosfet to see why no voltage on gate or try replace mosfet. By the way is this L6000 part of main power rail 19V?
https://youtu.be/e06pz1OEPZc

[mon2]

Re: Unable to Locate Power Supply Chip on HP Elitebook 840 G3

does a beep on the coil means a short... and why is it beeping if I get readings of 5ohms?

Yes, close enough to zero ohms to consider it a short. Do note that some low voltage rails are fine to have a low resistance reading. That is normal for cases like 0v8, 1v0, etc.

L60000 = 173 mv

I would start with this coil as the power rail appears to want to power up but is shutting down to some local event. Review the nearby mosfets and read off their markings. There should be 2 mosfets that will look similar - one for the high side / another for the low side for this switching power supply.

Also any nearby local IC that is likely to be the switching buck converter for that rail. What are the markings of the local IC near L60000? Maybe with enough info, we can locate a common schematic that will show us on how that IC should be wired up for a deeper investigation.

With the resistance reading of 40k ohms on this coil / power rail - the rail is not shorted. This is a good sign.