TOSHIBA L50-A-1EK VGSG MB REV 2.1 BRAK REAKCJI

Witam,
Płyta: L50-A-1EK VGSG MB REV 2.1
N14P-GV2-S-A1
Laptop wyłączył się momentalnie podczas pracy. Teraz brak reakcji na power.
Po podłączeniu zasilacza serwisowego delikatnie spada napięcie i próbkuje z 0A na około 0,080A - 0,090
podczas podłączania do gniazda ładowania słychać dziwne cykanie, pykanie na płycie.
Brak oznak grzejących się elementów. Proszę o wskazówki.

Hello!

Measure the resistance to ground on any pin of highlighted resistor. If the resistance is high (in kΩ range or greater), connect the power supply to the board and measure the voltage to ground on that resistor.

Hi,
Resistance is about 46 Ω.

Bezel018 писал(а):Resistance is about 46 Ω.

It is a short circuit to ground on main power rail.
Measure the resistances on all coils in reference to main power rail (highlighted resistor).
It is enough to specify the resistances, that are 60Ω or less.

The results are below.

Perform a short circuit test described here on main power rail (any pin of highlighted resistor in post #2). Limit the voltage to 19V.

GPU is heating.

Sorry, I missed your measurement on the GPU coils

It is bad one (or both) of transistors Q8700 or Q8703.

If is bad Q8700, also replace the Q8701.
If is bad Q8703, also replace the Q8704.



Before connecting power supply to the board specify the markings on chip U8700.

Q8700 have short circuit with gate. Ehhh I don't have this transistor. I must order it.

Q8700 I want order AON 7408 it is ok?
Q8701 I don't know which one I must replace. The mark is RA10 AZ T37M

The U8700 is OZ=OH N1K

If it is bad Q8700, I suggest you to also replace Q8701 for the safety, no matter if it seems ok, or not.

Bezel018 писал(а):Q8700 I want order AON 7408 it is ok?

Which is original one?

Bezel018 писал(а):Q8701 I don't know which one i must replace. The mark is RA10 AZ T37M

Q8701 is visible on the BoardView fragment in my previous post. RA10 = Vishay SiRA10DP.

Bezel018 писал(а):The U8700 is OZ=OH N1K

Measure the resistances between listed pins of U8700 (the damaged transistors should be removed from the board)
a) Between pin 1 and pin 2 of U8700
b) Between pin 2 and pin 20 of U8700.

If both resistances are high (in kΩ range or greater), just replace the transistors and test the board.

matic писал(а):Which is original one?

The original is SA14 AH T35M

matic писал(а):Measure the resistances between listed pins of U8700 (the damaged transistors should be removed from the board)
a) Between pin 1 and pin 2 of U8700
b) Between pin 2 and pin 20 of U8700.

I unsoldered damaged transistor and measured the resistance:
In both cases the resistance is high.

Bezel018 писал(а):The original is SA14 AH T35M

It is Vishay SiSA14DN.

Bezel018 писал(а):Q8700 I want order AON 7408 it is ok?

Yes, that would be a suitable replacement, but in my opinion it would be better to use the original one, because it is used in "Dual-phase" DC/DC converter.

Bezel018 писал(а):I unsoldered damaged transistor and measured the resistance:
In both cases the resistance is high.

Ok, replace both transistors and test the board.

Hi,
I replaced both transistors and board is working correctly.
Thanks for Help!