Acer 5740 fan spinning stops after short time

[danea]

Hi!
have a Acer 5740 wich is shutting down when in full load.
I check the temps and reach 100 degress in a matter of seconds,idle stays with 65-70.
Now,the problem i found is that the fan is not working properly,starts for a few second then stop.
Change thermal paste,clear the dust and reset EC.
Obviously since the fan is not working the processor can"t handle the temps.
Thinking update bios but i am afraid that it could shutting down in the process.(also the baterry is dead)
Any ideea how to solve the problem?
Thanks.

[mcplslg123]

Re: Acer 5740 fan spinning stops after short time

first, replace the fan and see if problem persists. Shutting down after how much time? Exact time every time or not??

[danea]

Re: Acer 5740 fan spinning stops after short time

hi and thanks for you response
the laptop is shutting down or freeze when put load to processor,monitoring the temp guess is normal since they arrived at 95-100 degrees.
now,the fan start spinning for 5 seconds when boot then is shutting down.
today i observe that the thermal monitor of the cpu is disable and think that not allowed the motherboard to properly activate the fan status.
searching for ways to enable it since the bios does not have such option.
my guess is i am dealing with a bad processor or motherboard.
reflash bios could help but as i said ,afraid not to have the notebook shutdown during te process. notice that the processor power is spec with 25w( HWMONITOR) wich is wrong since is an 35w processor.
Also found this page: https://www.hwinfo.com/forum/Thread-...-How-to-enable ,wich expose the same problem.

[mcplslg123]

Re: Acer 5740 fan spinning stops after short time

Either replace the fan first as suggested earlier or bypass fan circuit by doing the following:

01. Remove all wires from fan connector except black(gnd). In other words, only black wire will remain in the fan connector.
02. Now connect the red wire to any 3v source from mb.
03.Discard yellow wire for the time being.

Fan should remain always on with this method.

Try and update result.

[Th3_uN1Qu3]

Re: Acer 5740 fan spinning stops after short time

Fan is on 5V, if you connect to 3V it will spin with medium speed.

[mcplslg123]

Re: Acer 5740 fan spinning stops after short time

Fan is on 5V, if you connect to 3V it will spin with medium speed.

That wont harm as it will be always on. btw, this is just for test purpose.

[SMDFlea]

Re: Acer 5740 fan spinning stops after short time

On this model its usually the EC bios that gets corrupt,or the KBC dies. Flash the bios and EC with a programmer. The EC is MX25L1005

[danea]

Re: Acer 5740 fan spinning stops after short time

well,i could say i solve the problem
First, i was take the risk and flash a mod bios wich has thermal configuracion and many other advanced options enabled.Ventilating the motherboard with a plastic cover it was a succesful flashing despite my fear.
After that the fan had moments when kick on but it was behaving erraticaly.
Then i install notebook fan control with an acer 5738g config. file and that gives me total control of the fan since the bios is not properly control the fan.
I lost my programmer(thinking by a new one)otherwise this BIOS and EC dumps could be very useful.
Thank you all for your advise and your help.

[danea]

Re: Acer 5740 fan spinning stops after short time

Many thanks again.

[businessmind1988]

Re: Acer 5740 fan spinning stops after short time

i have come across this fault many times and i always measure a different 5v for the Red wire of the fan and it works good

[mcplslg123]

Re: Acer 5740 fan spinning stops after short time

i have come across this fault many times and i always measure a different 5v for the Red wire of the fan and it works good

exactly that's what i suggested him in the beginning but with 3v to be on safer side.

[danea]

Re: Acer 5740 fan spinning stops after short time

Grateful for your advise but not have a solder iron or a programmer.
Notebook fan control works great but only in windows envirroment,anyway believe that reprogramming the bios and ec could be a permanent solution.
imagine if i have to reinstall the OS have to dissasembly the notebook in order to properly ventilate de motherboard and cpu to not shutting down because of high temperatures.
And the red wire solution is also a good workaround.
Thanks.