Elitebook 840 G5 Bios Chip Soldering Question

[bykanovm]

Re: Elitebook 840 G5 Bios Chip Soldering Question

Understood. Left top 33 Ohm Right 15 Ohm. The pouch of the first ground contact is empty. thanks for answers

[mon2]

Re: Elitebook 840 G5 Bios Chip Soldering Question

See if the attached helps. This is from a 840 G6 schematic.

[bykanovm]

Re: Elitebook 840 G5 Bios Chip Soldering Question

I will clarify. These resistors go to the first pin of the chip. The bottom resistor, in the red rectangle, connects the first pin to ground, so it can't be small. I put a jumper in place of the upper resistor, the laptop started to turn on by itself, the consumption is weak 150 milliamps, the screen is dark, the fan is spinning. But I can't find the value of the second one.

[bykanovm]

Re: Elitebook 840 G5 Bios Chip Soldering Question

I marked contacts 1 and 2 in red in the photo. They brought it after another workshop, they said there were resistors there, and they were accidentally lost.
In the photo above you can see what the resistors are worth. The bottom resistor from pin 4 is 16ohm

[mon2]

Re: Elitebook 840 G5 Bios Chip Soldering Question

For each resistor pad, confirm to which pin is the bios chip mating with the part. Very likely, these are low resistance resistors to stop ringing. Value like 33R to 100R will be fine. If unavailable, should ok to even blob the pads with solder. Only suggest this if it is 100% known that the missing parts truly mate with the bios chip. Need to know to which pins on the bios chip before proceeding. If the pin is the power vcc pin then these are not a resistor but can be a local despike capacitor.

[bykanovm]

Re: Elitebook 840 G5 Bios Chip Soldering Question

Tell me the resistor values near the first contacts of the BIOS chip, please. I can't find a diagram.

[Azurain]

Re: Elitebook 840 G5 Bios Chip Soldering Question

Only if you see a metal pad under your bios chip. Then your bios chip must be soldered to the pcb large pad using a hot air tool.

Thank you for the information!

[mon2]

Re: Elitebook 840 G5 Bios Chip Soldering Question

Only if you see a metal pad under your bios chip. Then your bios chip must be soldered to the pcb large pad using a hot air tool.

[Azurain]

Re: Elitebook 840 G5 Bios Chip Soldering Question

Thank you for your response! Would you happen to know if I also need to solder the large center pads together as well?

[mcplslg123]

Re: Elitebook 840 G5 Bios Chip Soldering Question

The pads marked A & B are connected. manufacturer has given the option to solder two sizes of eeprom on this mb. The pads should be according to the chip you have de-soldered.

[Azurain]

Hi everyone,

I have an HP Elitebook 840 G5 that I am trying to get working again. I've removed the front bios chip (the 32mb one) and have run it through HP unlocker already. I've uploaded and verified the new bin, but am now experiencing an issue that has led me to believe I've been soldering the chip back to the motherboard incorrectly.

Essentially, after re-soldering the chip back into its place and reassembling the laptop, the charging light immediately flashes orange and white and then shifts to a solid white. The capslock and numlock lights blink seven times before shutting off. I've read the manual and this seems to indicate that "the embedded controller cannot find valid firmware" and this has led me to believe that I might be soldering the bios chip back on incorrectly.

The attached image shows my motherboard and the location where my bios chip should be. With reference to this image, I have been soldering the bios chip contacts to the pads above the yellow "A" letters. What I am unsure about is if the chip should actually be soldered to the smaller contacts above the green "B" letters. In addition, I don't know if the chip should actually contact the large rectangular contact in the middle or not.

The bios chip on the reverse side (the 16mb one) seems to contact only the smaller "B" pads but I haven't messed with that one at all.

If anyone could provide any guidance as to which way I should be soldering the bios chip back on, I would greatly appreciate it. Thank you for your time.