HP 250 G7 - nie włącza się

Witajcie

Laptop HP 250 G7 - płyta GPI 52 LA-J952P

Po podłączeniu zasilania nie włącza się. Świeci dioda w gnieździe zasilania. Pomiary oporności na cewkach głównych przetwornic - brak zwarć.
Napięcie +3ALW - startuje na kilka sekund, później znika.
Napięcie +5ALW - startuje na kilka sekund, później znika.

Rozlutowałem zworę PJ305, aby wykluczyć przeciążenie gałęzi, taka sama reakcja. Napięcie +5ALWP startuje na kilka sekund.

Pomiary przetwornicy PU302:

+19VB_5V - obecne
+5VALWP - start na kilka sekund
+5VL - obecne
VCC_5V - obecne (jednak 3,3V)
SPOK - po podłączeniu zasilania w stanie niskim (0,27V), po kilku sekundach 0V
ENLDO_3V5V - stabilne 9,5V
5V_3V_EN - po włączeniu zasilania 3,1V, po kilku sekundach 0V
5V_FB - dopóki jest napięcie na PL301 wynosi 0,63V

Podobnie zachowuje się PU301
+19VB - obecne
3VALWP - startuje na kilka sekund
+3VLP - obecne
SPOK - 3,3V przez kilka sekund
ENLDO_3V5V - stabilne 9,5V
5V_3V_EN - po włączeniu zasilania 3,1V, po kilku sekundach 0V
3V_FB - dopóki jest napięcie na PL302 wynosi 0,63V

Po podłączeniu zasilania do momentu odcięcia przetwornic CPU startuje. Pobór na zasilaczu 0,2A, po kilku sekundach spadek do 0,03A, a po kolejnej sekundzie 0A.
Czy jest to uszkodzenie przetwornicy PU302. Brak przejścia SPOK w stan wysoki i odcięcie?

Hello!

Measure the resistance between pin 9 of chip PU301 and pin 9 of chip PU302.

PU301 - pin 9 - 130k
PU302 - pin 9 - open

You probably measured the resistances to ground, but I asked about one measurement directly between pins 9 of both chips (put one probe to the pin 9 of PU301 and another probe to the pin 9 of PU302).

OK, my foult. Resistance between pin 9 PU301 and pin 9 PU 302 still "open line".

Snaeyk1980 wrote:Czy jest to uszkodzenie przetwornicy PU302. Brak przejścia SPOK w stan wysoki i odcięcie?

So the chip PU302 is fine. The "SPOK" of this chip is not used in this case.

Reflash the BIOS chip. Don't forget to save the old dump.

I flashed the BIOS with a file from the HP repository. Now the PCH starts for two seconds, then I see on the thermal imaging that PU301 is heating up. After a few seconds it cuts off and PU301 starts pulsing. In the old BIOS, both PCH and CPU started working for a few seconds.

Try with another BIOS dump, best with a cleaned ME-region.

I tested on several bioses with the ME region cleared. Without changes. When the board is started, the hybrid bridge warms up slightly, then the voltages are cut off and the PU301 converter pulsates gently.

Measure the voltages to ground on all coils for a short time, while the machine is turned on (the APU hybrid is warming up).

PL301 - 5,1 V
PL302 - 3,39 V
PLB1 - 3,1 V - slowly growing. It does not disappear when the converters are cut off.
PLV3 - 0 V
PLV4 - 0 V
PLW1 - 0 V
PLZ1 - 0 V
PLZ2 - 0 V
PLG1 - 0 V

Snaeyk1980 wrote:When the board is started, the hybrid bridge warms up slightly

Are you sure that the APU hybrid is warming up?
The voltages on the coils do not indicate that.

I am posting a link to a video showing the board's reaction after power is applied.

https://youtu.be/7UlLcq4COn8

You can't see it well in the video, but the PU301 converter is pulsating.

Does the power consumption of the board change after pressing to the power button (maybe only for a short time)?
Specify the power consumption (in mA) of the board before and after pressing to the power button.

Current consumption after connecting the power supply is 40mA. After cutting off the converters it drops to 0mA. After pressing the POWER button the board draws 40mA, then the converters are cut off and the current consumption drops to 0mA.
Once in a while after pressing the POWER button the converters are not cut off, the board then draws 30 - 40mA, the bridge in the hybrid heats up slightly.
The measurements are not accurate, I read them from an external power supply.

The APU hybrid is probably damaged.
You can try to reflow it, but it needs to be replaced for the permanent repair.