lenovo X240 sometimes it does not start

[poweron]

hello, this lenovo turns on the fan the leds but the screen remains black, if I turn it off and on again for 5 or 6 times it eventually turns on regularly, I have updated the bios but no I have solved it

[mon2]

Re: lenovo X240 sometimes it does not start

When screen is black, use a flashlight on the front of the display.

Can you see the video graphics on each power on?

If yes, then appears to be a failing backlight fault.

[mcplslg123]

Re: lenovo X240 sometimes it does not start

You can see if numlock key on usb kbd glows or not on every poweron attempt. That will give us an idea whether mb is posting everytime or not. Link schematic if available.

[poweron]

Re: lenovo X240 sometimes it does not start

the led of the usb keyboard do not light up and I forgot to mention that as soon as I turn it on, it emits 5 beeps - pause - 5 more beeps,i replaced the ram but the problem remains

[mon2]

Re: lenovo X240 sometimes it does not start

1) Remove the ram - power up - do you hear the same beeping pattern ?

2) Guessing that you will. Replace the RAM with a proper known good ram for this chassis.

[mcplslg123]

Re: lenovo X240 sometimes it does not start

Asking again, is schematic avlbl?? Measure voltage & resistance on all coils. Consumption on dc supply with ram/without ram?

[poweron]

Re: lenovo X240 sometimes it does not start

1) Remove the ram - power up - do you hear the same beeping pattern ?

2) Guessing that you will. Replace the RAM with a proper known good ram for this chassis.

without ram always emits 5 beeps-pause-5 beeps, then one beep-pause-three beeps-pause-three beeps-pause-one beep

[poweron]

Re: lenovo X240 sometimes it does not start

Asking again, is schematic avlbl?? Measure voltage & resistance on all coils. Consumption on dc supply with ram/without ram?

I have no possibility to measure power consumption, however I wanted to inform that the note works only after having insisted on turning it on for 5/6 times, so I don't think there are broken components on the main otherwise it would not have worked ... maybe it needs to rewrite the firmware ?
tank's