Dell M4800 LA-9772P - No light , no power ?

[Acnologia]

Hi to all!

I have 2 x Motherboards M4800 (1x is LA-9771P which is LVDS cable, and 1x LA - 9772P eDP Cable)

LA - 9771P came, faulty with damaged keyboard port, broken USB etc. almost bend in half , but you could hear the fan spin and lights go on.

LA - 9772P ,bought it from eBay as used some months back, worked like a charm , prime95 and dell diagnostic for hours to see if it's good ,just in case.All went well, so i stored it in the bookself ,until i got the new plastics that i wanted from China.

Yesterday, all came, so i began to assembly , but no reason the LA-9772P, board suddenly didn't post anything ,not even lights, nothing. I removed everything from it, just in case something was making a problem ,but again nothing, only the board + CPU and power button ,but again it's dead.

I made, CMOS, RAM Swap, even Clean BIOS ME from SMDFlea which i found from the forum , even got the BIOS from the LA-9771P and tried just in case nothing.

So i began reading around , and saw the MOSFETs close to the "Power jack" measured and i saw some funny results, so i got the MOSFETS (from the 9771P ) and plugged them into the 9772P ,again nothing not even light .Returned them ,to the 9771P and the 9771P spins.

So, the situation is really frustrated to my knowledge .

The schematics show that the PQ5 / PQ701 ,both are "SI7149DP",but on the chip it self (under the microscope ) i see "MDU6303".

What can result to the sudden death ?It's really strange.

[SMDFlea]

Re: Dell M4800 LA-9772P - No light , no power ?

Hi to all!

I made, CMOS, RAM Swap, even Clean BIOS ME from SMDFlea which i found from the forum , even got the BIOS from the LA-9771P and tried just in case nothing.

So i began reading around , and saw the MOSFETs close to the "Power jack" measured and i saw some funny results, so i got the MOSFETS (from the 9771P ) and plugged them into the 9772P ,again nothing not even light .Returned them ,to the 9771P and the 9771P spins.

You used the bios from the LA-9771P ,did you clean the ME before you tried it as its come from another machine thats been booted already,so the ME would be initialised (dirty).

What were the funny results ? ,do you mean, no voltage,fluctuating etc . Did you try a different power jack and charger .Is the charger a genuine one. Did the CMOS battery voltage check ok .

[Acnologia]

Re: Dell M4800 LA-9772P - No light , no power ?

You used the bios from the LA-9771P ,did you clean the ME before you tried it as its come from another machine thats been booted already,so the ME would be initialised (dirty).

What were the funny results ? ,do you mean, no voltage,fluctuating etc . Did you try a different power jack and charger .Is the charger a genuine one. Did the CMOS battery voltage check ok .

To answer in detail your questions.
Yes, but even if the BIOS was going to be dirty , there wasn't not even lights on the board, i mean the plug-in light , without even turning on.
I measured the central line of mosfets all are clear..

(PQ701,PQ5 ,PQ1008,PQ1009,PQ1004,PQ1003 all stable with 19volt etc. )again no sign of life.

It was really sudden.
Yes, the charger is brand new and too powerfull genuine Dell . 19.5 10.8A
Yes, i have checked the extra small details.

The "old board" 9771P with the same parts, shows lights and fan spin without display ,but as i said, it's really damaged.

The "new board" that suddenly stopped, didn't even show life , nor a sign nor a light . (When some time ago it was working just fine)
It was really sudden.

[SMDFlea]

Re: Dell M4800 LA-9772P - No light , no power ?

Check the PR9 resistor voltage and ALW voltages