HP Notebook 17-BY [SNAPE92 6050A3107701 MB A01] - Fan speed 100% all time

Hello

I have HP Notebook 17-BY 10th gen laptop (SNAPE92 6050A3107701 MB A01)

The problem is the fan is constantly stuck at full speed, from the momnet you press the power button, even in the bios screen too. The cpu tempreatures read normal around 30 degrees. I have updated to the latest BIOS via HP exe with no change.

I have checked the fan with a PSU to see it isnt stuck at full speed and it was ok. i have programmed a clean ME region bios file and a new EC file (from vinafix). This did not help problem.

There are no schematics available currently, I measured the fan connecter pins
pin 1 = 5v
pin 2 = GND
pin 3 = 1.7V
pin 4 = 1V (rises to 1v then drops to zero and cycles)

res to ground
pin 3 = 78k ohms
pin 4 = 10k ohms

pin 3 connects with pin 30 of EC (IT8987E) and pin 4 connects to pin 47 via a 4.7k ohms resistor. without schematics i am unsure how to proceed, i would appreciate some professional advice. thank you

Hello!

Do you have an oscilloscope?
If so, measure the voltages to ground on pins 3, 4 of fan connector with oscilloscope.

Hi matic

I do have a very basic oscilloscope, i have taken measurements of pin 3 and pin4 of the fan conector and converted the video to gif, hopefuly this is sufficent. You can see a cycle on pin4 that would match with the decreasing voltage from 1v to 0v and repeating.

Pin4


Pin3

Which KBC chip is on this board?

The KBC is IT8987E

Start with reflashing the BIOS chip.
If it does not change anything, reflash the KBC chip as well.

I have already programmed a new BIOS file and KBC file too, still with no change. It may be somthing with the tempreature sensing, but without the schematics i am having trouble locating the relevant components.

Install a Open hardware monitor and check, if the temperatures of the CPU and GPU (if it is on the board) are displayed correctly.

The tempreatures appear normal , as low as 25 degrees when idle.

It seems the issue is not related to the temperature sensing.

Try to reflash the BIOS chip with a cleaned ME-region.

Ok, im unsure as what the fault could be, as mentioned in the original post i have programmed a new BIOS with a cleaned ME region and it did not help with the problem.

Try to replace the KBC chip.

Sorry for the delay. I have swapped the KBC chip and programmed the original KBC firmware and still the fan is at full speed.

Do you know where to look next? I can post the BIOS and KBC files to inspect, but i am almost certain they are ok.

Try with another fan.
If you don’t have the same fan for the test, I think it should also work with any other 4-pin fan from any other laptop. Make sure the fan pin out matches before connecting it to the board.

Ok, i used on old Pavilion 15-AU fan and desoldered the wires and connector and used the connector/wires from the fan in the 17-BY laptop in question, and it sounds like it has worked! The fan is running quietly as normal, so it looks like it was the fan all along.

Thanks for the advice matic

Would that be somthing down to the PWM circuit on the fan itself?

KenM0560 napisał(a):Would that be somthing down to the PWM circuit on the fan itself?

Yes, the PWM controller circuit on the fan board is damaged. There is usually a chip on that board, which output is in short circuit. This chip needs to be replaced, but I think it’s definitely not profitable to play with, because it is usually not simple to disassemble / reassemble the fan without braking something.

Ok I see, yes there are no screws holding the fan together just plastic clips. I will order a new one to replace. Thanks for your help, ill mark your answer as "Helped"