Lenovo Legion 5 15ARH05H - zbita matryca, brak reakcji na włącznik

Cześć.
Oznaczenia z płyty:GY55M, N, T, Q, R, S, W, V, NM-D281 REV: 1.0. Laptop podczas pracy został zrzucony na podłogę, zbita matryca, przestał się włączać. Pobór prądu po podaniu napięcia wynosi 0,15A, brak reakcji na włącznik. Bios przeprogramowałem 2 wsadami, bez zmian, upaleń na płycie nie ma, nic się nie grzeje. Poniżej podaję napięcia i rezystancję na cewkach i proszę o dalsze wskazówki:
PL2002 - 5,14V; 13,5kΩ
PL2001 - 3,4V; 5,7Ω
PL2701 - 0V; 88Ω
PL5105 - 0V; 0Ω
PL7701 - 5,14V; 14kΩ
PL5101 - 0,01V; 0,7Ω
PL5102 - 0,01V; 0,7Ω
PL5103 - 0,01V; 0,7Ω
PL5104 - 0,01V; 0,7Ω
PL2301 - 0V; 12Ω
PL8202 - 0V; 66Ω
PL8201 - 0V; 66Ω
PL7504 - 0V; 0,2Ω
PL7503 - 0V; 0,2Ω
PL7502 - 0V; 0,2Ω
PL7501 - 0V; 0,2Ω
PL1401 - 0V; 0Ω
PL101 - 0,23V; 4,5MΩ
PL1301 - 0V; 0Ω.

arjuredi писал(а):PL5105 - 0V; 0Ω
PL1401 - 0V; 0Ω
PL1301 - 0V; 0Ω

Hello!
Are you sure there are dead shorts to ground on those three coils?
Did you measure the resistances with all power sources disconnected from the board?

Yes, exactly. I changed the batteries in the meter and it comes out the same. After connecting the probes, I have a resistance of 0.001Ω and when measuring on the coils, I also have 0.001Ω. I called the customer yesterday and he said that before he brought the laptop, they connected 2 displays, but he doesn't remember which ones.

Remove the coil PL1301 from the board and check on which side of this coil is a short circuit to ground. If the short circuit is present on the system side (power rail "+1.8VALW"), perform a short circuit test described here. For a short circuit test limit the voltage to 1.8V.

After the short-circuit test, UC1 is finally heated up.

So the APU processor is unfortunately damaged and needs to be replaced.
First remove the APU from the board and remeasure the resistances to ground on coils PL1301, PL1401, PL5105.

Do you know the factory markings on this chip, because there is nothing stamped on the core and I don't know exactly what to look for?

The core of these chips is originally unmarked. The markings are printed on the metal edge of the chip.

The exact marking of the chip is 100-000000100 (It's an AMD Ryzen R5-4600H).

PL1301 - 34kΩ
PL1401 - 1,88MΩ
PL5105 - 5MΩ

The resistances seems fine. Solder a functional APU to the board.

Markings 100-000000100 means Ryzen 5 R5-4600H?

Yes, exactly.

I have solder a new APU and now I have these resistance:
PL1301 - 4,28 kΩ
PL1401 - 30 Ω
PL5105 - 6,6 Ω
I have no reaction on power button.

Remeasure the resistances to ground on all coils.

PL2002 - 5,13V; 13,7kΩ
PL2001 - 3,4V; 3,7kΩ
PL2701 - 0V; 146Ω
PL5105 - 0V; 5,5Ω
PL7701 - 5,13V; 14kΩ
PL5101 - 0V; 2,4Ω
PL5102 - 0V; 2,4Ω
PL5103 - 0V; 2,4Ω
PL5104 - 0V; 2,4Ω
PL2301 - 0V; 10Ω
PL8202 - 0V; 60Ω
PL8201 - 0V; 60Ω
PL7504 - 0V; 0,5Ω
PL7503 - 0V; 0,5Ω
PL7502 - 0V; 0,5Ω
PL7501 - 0V; 0,5Ω
PL1401 - 0V; 26Ω
PL101 - 0,23V; 4,5MΩ
PL1301 - 1,8V; 4,2kΩ.

- Measure the voltages to ground on both pins of quartz YC1. It's best to measure it with an oscilloscope. If you don't have it, measure with a multimeter.
- Measure the voltage to ground on pin 90 of KBC chip.