Dell Latitude E7440, LA-9591P, not booting suspecting VCC_CORE

[ayavilevich]

Hello everyone,

A E7440 laptop stopped working. Not booting. Nothing is shown on the screen. Power and charge LEDs will light (on and off in sequence) when plugged in. Fan not spinning except for when pressing the power button to turn off the device.

The board is LA-9591P. I have schematics and board view.
The processor is i7-4600U. Getting warm/hot when plugged in.

I took the board out and tested some power rails. All seems ok except that I don't know what should be the right core voltage. VCC_CORE measures at 1.74V. Is that right?
If not right, what could be wrong and is there any chance the CPU is still ok?
If that is right, what should I check next?

For the record I tested the following rails:
+5V_ALW - ok 5V
+3.3V_ALW - ok 3.3V
+3.3V_ALW_PCH - ok 3.3V
+3.3V_RTC_LDO - ok 3.3V
*
+3.3V_SUS - ok 3.3V
+1.35V_MEM - ok 1.34V
*
+5V_RUN - ok 5V
+3.3V_RUN - ok 3.3V
+0.675V_DDR_VTT - ok 0.681V
+1.05V_RUN - ok 1.05V

+VCC_CORE - ? 1.74
+3.3V_M - ok 3.3V
+1.05V_M - ok 1.062V

Thanks in advance,
Arik.

[Sephir0th]

Re: Dell Latitude E7440, LA-9591P, not booting suspecting VCC_CORE

Test with Known good DDR3L RAM, to start with. From there you should rule out a corrupted BIOS first.

[ayavilevich]

Re: Dell Latitude E7440, LA-9591P, not booting suspecting VCC_CORE

Test with Known good DDR3L RAM, to start with. From there you should rule out a corrupted BIOS first.

I tried two different DIMMs. Both same behavior. I don't have something else right now to try.
If I install no RAM then the LEDs light up in a special "no ram" LED code.

How can I rule out a corrupted BIOS?
This laptop doesn't have an official BIOS recovery process.
Any suggestions or guides on dumping or flashing BIOS for this model?

[TuanTongbadcaps]

Re: Dell Latitude E7440, LA-9591P, not booting suspecting VCC_CORE

I tried two different DIMMs. Both same behavior. I don't have something else right now to try.
If I install no RAM then the LEDs light up in a special "no ram" LED code.

How can I rule out a corrupted BIOS?
This laptop doesn't have an official BIOS recovery process.
Any suggestions or guides on dumping or flashing BIOS for this model?

You should try flashing the bios chip with another good rendering from the forum to rule it out.

[ayavilevich]

Re: Dell Latitude E7440, LA-9591P, not booting suspecting VCC_CORE

You should try flashing the bios chip with another good rendering from the forum to rule it out.

Does this necessary mean removing the flash chips from the board or can they be programmed in circuit?
Any guides for that?

[ayavilevich]

Re: Dell Latitude E7440, LA-9591P, not booting suspecting VCC_CORE

What about VCC_CORE? Is 1.74V correct for this laptop?

[Sephir0th]

Re: Dell Latitude E7440, LA-9591P, not booting suspecting VCC_CORE

Intel 4th Gen CPUs uses Fully Integrated Voltage Regulator ( FIVR ) and 1.8V there is absolutely fine. Otherwise I wouldn't had suggested to continue with BIOS.

[Vesko356]

Re: Dell Latitude E7440, LA-9591P, not booting suspecting VCC_CORE

Take Sephir0th's advice and flash the bios first. You can use the files (flash both) in this post (tested by me, I've also cleaned the ME Firmware - the dump is for sure 100% OK):
https://www.badcaps.net/forum/showpo...9&postcount=47

.

[ayavilevich]

Re: Dell Latitude E7440, LA-9591P, not booting suspecting VCC_CORE

Thank you Sephir0th, TuanTongbadcaps and Vesko356!

Got a CH341A programmer and a 8-SOIC clip. Flashed good firmware from the forum on both chips. Laptop works and will be put to good use.

A win for the right to repair!