Acer 8943G - uruchamia się tylko na sekundę

matic ha scritto:It seems better now.
Also measure the voltage to ground on pin 12 of chip PU7 for a short time, when the machine is turned on.

PU7 pin 12 - 0,32V max

Measure the voltages to ground on pins 2, 3 of transistors Q8, Q9, Q11 for a short time, when the machine is turned on.

Transistors Q8, Q9, Q11 pin count:

matic ha scritto:Measure the voltages to ground on pins 2, 3 of transistors Q8, Q9, Q11 for a short time, when the machine is turned on.

Transistors Q8, Q9, Q11 pin count:
[ Obrazek ]

Q8
1 - 2,15V
2 - 3,37V
3 - 2,49V

Q9
1 - 2,14V
2 - 2,16V
3 - 2,09V

Q11 (cannot find him but I think is this next to Q8 and Q9)
1 - 3,38V
2 - 3,37V
3 - 2V

Are this measurements correct?
Pin 1 of transistor Q9 is connected to the ground, but you measured 2,14V there?

matic ha scritto:Are this measurements correct?
Pin 1 of transistor Q9 is connected to the ground, but you measured 2,14V there?

[ Obrazek ]

New measurements, my mistake.

Q8
1 - 3,38V
2 - 3,37V
3 - 2,49V

Q9
1 - 0V
2 - 1,83V
3 - 3,35V

Q11
1 - 3,38V
2 - 3,37V
3 - 1,9V

Measure the resistance between pins 1, 2 of transistors Q8, Q11.

If both resistances are high (in kΩ range or grater), remove the transistors Q8, Q11 from the board and remeasure the voltages to ground on all pins of transistor Q9 for a short time, when the machine is turned on.

matic ha scritto:Measure the resistance between pins 1, 2 of transistors Q8, Q11.

If both resistances are high (in kΩ range or grater), remove the transistors Q8, Q11 from the board and remeasure the voltages to ground on all pins of transistor Q9 for a short time, when the machine is turned on.

Q9
1 pin - 0 V
2 pin - 2,9 V
3 pin - 3,36V for a while then 0,05V

if Q8 and Q11 are removed laptop won't turn off immediately

tomaszpo ha scritto:Q9
1 pin - 0 V
2 pin - 2,9 V
3 pin - 3,36V for a while then 0,05V

This voltages are correct. The same voltages should be with soldered transistors Q8, Q11.
Check the transistors Q8, Q11.

soldered Q8 with Q11 out (laptop not turn off)
Q8 pins
1 - 3,38V
2 - 3,38V for a while then 0,05V
3 - 3,38V

soldered Q11 with Q8 out (laptop turn off after 1 sec)
Q11 pins
1 - 3,38V
2 - 3,37V
3 - max 1,41V

Q11 (AO3413) seems damaged. Replace it.

matic ha scritto:Q11 (AO3413) seems damaged. Replace it.

I replaced it 2 times and the same effect laptop after 1 sec is off.

Q11 voltage and resistances to ground
1 - 3,38V (568 Ohm)(in the first measurement, the meter had to switch and showed me 3.35k Ohm, so I excluded resistances, but I repeated the measurement now)
2 - 3,37V (9,09k Ohm)
3 - max 2,14V (7,2k Ohm)

Remove the transistor Q11 from the board and inject 3,3V from the laboratory power supply to pad 3 on the place of transistor Q11. What electrical current flows from the laboratory power supply in this case?

matic ha scritto:Remove the transistor Q11 from the board and inject 3,3V from the laboratory power supply to pad 3 on the place of transistor Q11. What electrical current flows from the laboratory power supply in this case?

1,5mA

Try to reflow the GPU.
If it does not change anything, replace it.

matic ha scritto:Try to reflow the GPU.
If it does not change anything, replace it.

Reflow doesn't change anything. Could I check anything else because I dont have heater for replace BGA?

I noticed, and actually heard that when starting this laptop with Q11 soldered, it starts for a second and I hear a pop as if a relay was activated.

tomaszpo ha scritto:Reflow doesn't change anything. Could I check anything else because I dont have heater for replace BGA?

If you don't have a BGA station, you probably didn't do a reflow, just diagnostic heating.
The reflow means heating the BGA chip to a temperature that the solder balls under it melts.

I think it is hard to do anything else here without the BGA machine.