Dell latitude 5490 la-f401p no display

[Bisketti]

Help needed, I have 2 La-F401p both have no display. No spillage. Lcd test works fine . Both draw around 500ma then drop off to 300ma.
I have tried various bios dumps.
Lcd test was fine.
No sign of spillage /blown components.
Data pins on usb ports are not reading short to ground.
No short on coils .
voltage on all coils
PCH_PLTRST# is present 3.3v
3.3v/5v are present

[mcplslg123]

Re: Dell latitude 5490 la-f401p no display

DRAMRST# ststus?

[Bisketti]

Re: Dell latitude 5490 la-f401p no display

1.2v

[Sephir0th]

Re: Dell latitude 5490 la-f401p no display

Check for ripped components/damaged tracks near the BIOS chip and the CPU then. Normally the BIOS should initialize at this point. Maybe the firmware was not flashed in a proper way by any chance?

[Bisketti]

Re: Dell latitude 5490 la-f401p no display

DRAMRST# ststus?

Check for ripped components/damaged tracks near the BIOS chip and the CPU then. Normally the BIOS should initialize at this point. Maybe the firmware was not flashed in a proper way by any chance?

Hi thanks for the input. It didnt look like the bios had been worked on I think its original bios as I got in 2 with same issue.. Nothing I can see as far as missing components or track damage. Il keep working on the bios

[Magnusa2]

I HAVE ALSO SAME PIECE. DELL 5490 LA-F401P NO DISPLAY . I HAVE SAME 6 PIECES .ANY SOLUTION FOR THIS. I DID ALREADY BIOS.

[mon2]

Video through hdmi port working?

[Magnusa2]

no hdmi display also not coming

[Magnusa2]

Video through hdmi port working?

no

[Magnusa2]

no

now i did one bios one time display coming . after no . i use dell og charger with battery

[mon2]

Review the power up sequence chart on sheet # 46 in the schematics. Need to review the first one where the voltage is absent that will halt the boot process.

Update:

Just read your last post. Are you using the barrel style power adapter? What are the specs? Is it the exact and recommended power adapter for this model?

Dell power adapters (as documented many times in this forum) use a single wire communication to determine if the power adapter is worthy enough to power these pigs of laptops.

Carefully measure the voltage to ground of the following points of interest:

NB_PSID @ PL3

PS_ID @ PR4

If the adapter ID mechanism is broken (quite common) - then the laptop will not boot as it believes the power adapter is wimpy and incapable of being used.

[Magnusa2]

Review the power up sequence chart on sheet # 46 in the schematics. Need to review the first one where the voltage is absent that will halt the boot process.

Update:

Just read your last post. Are you using the barrel style power adapter? What are the specs? Is it the exact and recommended power adapter for this model?

Dell power adapters (as documented many times in this forum) use a single wire communication to determine if the power adapter is worthy enough to power these pigs of laptops.

Carefully measure the voltage to ground of the following points of interest:

NB_PSID @ PL3

PS_ID @ PR4

If the adapter ID mechanism is broken (quite common) - then the laptop will not boot as it believes the power adapter is wimpy and incapable of being used.

THANKS FOR THE INFORMATIONS.PSID IS OKEY 3.3
STILL I FEEL BIOS ISSUE YOU CAN REPAIR MY BIOS
BECOUSE NOW I HAVE SIX MORE PIECES SAME ISSUE

[mon2]

You will have to post the bios image and request inside the dedicated BIOS forum.

[Magnusa2]

You will have to post the bios image and request inside the dedicated BIOS forum.

ok

[Magnusa2]

hii
i have 5490 (la-f401p) no power. 3.3v alw 5v alw not present. resistense normal. pwr src coming 12.5
any solutions ?