Dell Latitude 5404 płyta core_combo_B2 niskie napięcie +PWR_SRC

Cześć, próbuję ożywić płytę core_combo_B2 v. 2.2
Płyta miała zwarcie od razu po podpięciu zasilacza. Uszkodzony był charger BQ24715 PU5802. Wypalił nawet jeden pad (n.2 ACP).
Podmieniłem charger. Zwarcia nigdzie nie zaobserwowałem. Zasilacz awaryjny zasila poprawnie 19V. Pobór prądu znikomy poniżej 0.1A. Niestety charger nie działa prawidłowo. Napięcie +PWR_SRC wynosi ok 5V.
Poniżej pomiary rezystancji i napięcia na chargerze.
Będę wdzięczny za wszelką pomoc.

PU5802
1 - 590kΩ / 19V
2 - 590kΩ / 19V
3 - 500kΩ / 18,5V
4 - INF / 21V
5 - 84kΩ / 1,5V
6 - 61kΩ / 3V
7 - 860kΩ / 0V
8 - 20kΩ / 0,8V
9 - 20kΩ / 0,8V
10 - 87kΩ / 3,8V
11 - 3,8MΩ / 0,8V
12 - 1,2MΩ / 4,6V
13 - 1,2MΩ / 4,6V
14 - GND
15 -205kΩ / 0V
16 - 91kΩ / 5V
17 - 4MΩ / 6,4V
18 - 1,4MΩ / 4,6V
19 - 1,1MΩ / 4,6V
20 -300kΩ / 5,2V

Hello!

- Measure the resistance to ground on coil PL5800.
- Measure the resistance to ground on pin 8 of transistor PQ9531.
- Measure the voltages to ground on pins 1, 4, 8 of transistors PQ5103, PQ5931.

matic написав:- Measure the resistance to ground on coil PL5800.

PL5800 - 600kΩ

matic написав:- Measure the resistance to ground on pin 8 of transistor PQ9531.

I don't have it on the schematic

matic написав:- Measure the voltages to ground on pins 1, 4, 8 of transistors PQ5103, PQ5931.

PQ9531
1,2,3 - 105kΩ
4 - INF
5,6,7,8 - 300kΩ

PQ5103
1,2,3 - 160kΩ
4 - 92kΩ
5,6,7,8 - 106kΩ

matrixmm написав:

matic написав:- Measure the resistance to ground on pin 8 of transistor PQ9531.

I don't have it on the schematic

Sorry, my fault. I mean PQ5931.

matrixmm написав:

matic написав:- Measure the voltages to ground on pins 1, 4, 8 of transistors PQ5103, PQ5931.

PQ9531
1,2,3 - 105K
4 - INF
...

You didn't specify the measurement units, so we don't know what these measurements are. "105K" means nothing. If "K" is a prefix and means "kilo", it must be written in lowercase letters.
But "105k" may still mean different things, for example 105kg, 105kV, 105kF, 105kΩ, 105kA, ... so edit your previous post with the measurement units.
If I were to guess, I'd say it's resistance measurements, but I ask for voltages.

matic написав:You didn't specify the measurement units, so we don't know what these measurements are. "105K"...

Thanks for paying attention. I corrected all of them.

matic написав:If I were to guess, I'd say it's resistance measurements, but I ask for voltages.

I'am, sorry, my fault.

PQ9531
1,2,3 - 19V
4 - jumps between 4V-7V
5,6,7,8 - 18,8V

PQ5103
1,2,3 - 19V
4 - 1,7V
5,6,7,8 - 19V

Edit:
I noticed that the PR5800 has 19V on both legs. However, on n.20 of the PU5802 there is 5V. This led me to the damaged PR5825 resistor. I'll look for one and solder it.

Edit 2:
Beautiful
After replacing the PR5800, the board works. The 3V/5V converter started normally. The disc starts up. The screen backlight doesn't work yet, but it may be the matrix's fault.
Last question, is 9V on PL5800 ok? is +PWR_SRC=9V ok?

matrixmm написав:Last question, is 9V on PL5800 ok? is +PWR_SRC=9V ok?

Yes, that's perfectly fine.

Thank you very much for your help and valuable advice. The computer is working. I'm closing the topic.