hp elitebook 840 g2 fan always running

[dqtech]

even after shutdown, fan keep running max rpm until battery drain....also when i plugged in the charger, fan will running max rpm it self even not turn on yet...what could be the problem ya?...here i attach the video

[mcplslg123]

Re: hp elitebook 840 g2 fan always running

DC-DC coverter,aka load switch, is very likely bad. Its a14 pin IC with 7 pins on each side. Replace them one by one and see if the problem goes away.There can be 2-3 such load switches.

[dqtech]

Re: hp elitebook 840 g2 fan always running

DC-DC coverter,aka load switch, is very likely bad. Its a14 pin IC with 7 pins on each side. Replace them one by one and see if the problem goes away.There can be 2-3 such load switches.

do you mean this ic sir?...L6100 3valwp / L6150 5valwp

[dqtech]

Re: hp elitebook 840 g2 fan always running

i test diode mode on 5v coil L6150 but not found any short here....any guide here?

[Sephir0th]

Re: hp elitebook 840 g2 fan always running

Load-Switch!

If you have no idea what it is and how to search for a internal(!) shorted component, then share link to schematics, boardview or simply high quality pics of your board, please.

[dqtech]

Re: hp elitebook 840 g2 fan always running

Load-Switch!

If you have no idea what it is and how to search for a internal(!) shorted component, then share link to schematics, boardview or simply high quality pics of your board, please.

this is the schematic...only found COMET instead of CHICLET

MOD Edit - Link to schematic https://www.badcaps.net/forum/showthread.php?t=85724

Reminder: rules and organization of this section
https://www.badcaps.net/forum/showthread.php?t=117483
.

[Sephir0th]

Re: hp elitebook 840 g2 fan always running

Q7100 for example if it exists by any chance

[dqtech]

Re: hp elitebook 840 g2 fan always running

Q7100 for example if it exists by any chance

q7100 got 5v...but q7050 only read 1.4v instead of 3v...is that right?

[natic]

Re: hp elitebook 840 g2 fan always running

q7100 got 5v...but q7050 only read 1.4v instead of 3v...

Each transistor has more than one pin. If you write "q7100 got 5v" we don't know which pin exactly do you mean. So, always specify the pin number, otherwise the measurement is pointless and says nothing to us.

Transistors Q7100, Q7050 pin count:



So, please measure the voltages to ground on pins 1, 3, 4 of transistor Q7100 when the machine is turned off.

[dqtech]

Re: hp elitebook 840 g2 fan always running

Each transistor has more than one pin. If you write "q7100 got 5v" we don't know which pin exactly do you mean. So, always specify the pin number, otherwise the measurement is pointless and says nothing to us.

Transistors Q7100, Q7050 pin count:



So, please measure the voltages to ground on pins 1, 3, 4 of transistor Q7100 when the machine is turned off.

im not doing anything on this motherboard yet, just rest for 1 night...right now when i plugged in the charger, the fan not spin anymore and no indicator light at all...like already dead...but 19v/3v/5v present...press power button no respond

Q7100
pin 1 5v
pin 2 5v
pin 3 0v
pin 4 0v
pin 5 5v
pin 6 5v

Q7050
pin 1 1.3v
pin 2 1.3v
pin 3 0v
pin 4 0v
pin 5 1.3v
pin 6 1.3v


i replace Q7050, now it read normally 3v on pin 1/2/5/6...0v on pin 3&4

[natic]

Re: hp elitebook 840 g2 fan always running

i replace Q7050

Which transistor exactly did you use for the replacement?

- Measure the resistance to ground on pin 4 of transistors Q7050, Q7100.

[dqtech]

Re: hp elitebook 840 g2 fan always running

Which transistor exactly did you use for the replacement?

- Measure the resistance to ground on pin 4 of transistors Q7050, Q7100.

i replace Q7050 AO6424L with FDC653N

Q7050 pin 4 = 8k ohm
Q7100 pin 4 = 15k ohm

[natic]

Re: hp elitebook 840 g2 fan always running

- Measure the voltages to ground on pins 14, 15, 31, 64, 74 of KBC chip.

- Measure the voltage to ground on pin 73 of KBC chip in the following cases:
a) Power button released.
b) Power button pressed.