Lenovo G50-80 ALCU3/ACLU4 NM-A361 Rev 1.0 nie włącza się

Cześć,
płyta po zalaniu(okolice zaznaczone na czerwono):


Po naprawie(wymiana skorodowanych elementów, poprawa ścieżek i zabezpieczenie soldermaską UV) podziałała kilka miesięcy i przestała się włączać. Po podłączeniu zasilacza znikomy pobór prądu, pojedyncze mA. Wciśniecie włącznika powoduje zapalnie diody zasilania. Pobór prądu wzrasta minimalnie. Kamera termowizyjna nie pokazuje żadnego elementu wyróżniającego się, co jest raczej normalne przy płynącym tak małym prądzie. Przytrzymanie włącznika powoduje zgaśniecie diody zasilania. Przeszukując internet trafiłem na wpis jednego z użytkowników z wynikami jego pomiarów. Na czerwono odniosłem swoje wyniki, pomiar przy świecącej diodzie:


Wynika z tego że mam tylko napięcia Always ON. Co warto sprawdzić w kolejnych krokach?
Pozdrawiam

Measure the voltages on pins 1, 5, 6, 8, 9, 12, 15, 16, 17, 20 of PU1207.

Hi, measurement results:
1-0V,
5-0V,
6-1.81V,
8-1.36V,
9-0V,
12-5.09V,
15-4.88V,
16-0V,
17-3.36V,
20-0V.

Measure the voltages on pins 12, 18, 21, 26, 35, 72, 86, 87, 93, 97, 107, 108, 111, 128 of KBC.
Measure the voltages on pin 110 of the KBC in the following cases:
at power off
with power on pressed
at power on

12-1.75V
18-0V
21-0V
26-3.39V
35-3.39V
72-1.43V
86-0V
87-0V
93-3.39V
97-3.39V
107-0V
108-0V
111-3.38V
128-3.39V

110- ON/OFF-3.35V, pressed on-0v

Measure the resistance to ground on pin 86 of KBC.
If it's high:
Replace the bios and remember to save the old one.
If voltage does not appear, replace the KBC.
If the voltage remains at 0v the PCH is most likely faulty.

I have a resistance of 18k on this pin. I figured it was high. I prepared and uploaded another bios, unfortunately no response.
The voltage on this pin is 3.39V, when I press the switch (the LED is on) it drops to 0. In this case, is it left to replace the KBC? Do I need to program it or will a relocated one from another board work?

If the voltage on pin 86 of the KBC is at 3v before pressing the start button and switches to 0v when pressed and returns to 3v when released then this is OK.
Remeasure, after pressing the start button, all pins of the KBC previously at 0v.

Hi. I have taken the measurements again. Only one value differed from what I measured earlier.
18-0V
21-0V
86-0V
87-0V --> 2.6V
107-0V
108-0V

I'm afraid that there may be some single signal missing on the board(invisible corrosion of a path or component). Just how to locate it?

Measure the voltage on pin 106 of KBC.
The voltage on pin 86 of the KBC must be 3v to work.
Solutions:
Replace the bios and remember to save the old one.
If not solve replace the KBC.

Machine написав:Measure the voltage on pin 106 of KBC.

0V

Machine написав:Replace the bios and remember to save the old one.

I wrote earlier that I uploaded a clean bios. I used it before and it worked.

Machine написав:If not solve replace the KBC.

I have a second board with such a chip and a different fault. I repositioned it. The symptoms remained exactly the same.

If pin 86 does not supply 3v to the PCH there is no response from the PCH on pins 106, 18, 21 of the KBC.
Probable possible failure on the PCH contained in the APU.