Acer 8943G - uruchamia się tylko na sekundę

Model : Acer 8943G
Board id : DA0ZYAMB8D0 Rev:D

Laptop najprawdopodobniej po zwarciu na zasilaczu lini + i -, po naciśnięciu przycisku power na sekundę zapala się dioda power, startuje wentylator po czym laptop się wyłącza, po podłączeniu zasilacza na diodzie PD2 pojawia się napięcie 19V. Co mogło najprawdopodobniej się uszkodzić i co sprawdzić w pierwszej kolejności.

Hello!

Measure the voltages to ground on all coils for a short time, when the machine is turned on.
Measure the voltages to ground on all pins of transistor PQ13.

PQ13 (laptop off)
1-pin - 9,06V
2-pin (not soldered) - 18,95V
3-pin - 18,95V

Coils (laptop on)
PL5 both pins - 1,83V
PL6 both pins - about 3,20V
PL7 both pins - about 1,53V
PL8 both pins - maximum 0,6V
PL9 both pins - maximum 0,3V
PL10 both pins - 1,11V
PL11 both pins - 1,10V
PL12 (I think because I don't see number but's near PL11) both pins - 1,10V
PL13 both pins - maximum 0,5V
PL14 both pins - 3,38V
PL16 both pins - 1,06V
PL17 both pins - 5,11V

Measure the resistance to ground on all coils.

Measure the voltage to ground on pin 13 of charger chip PU2.
Measure the voltage to ground on pin 114 of KBC chip for a short time, when the machine is turned on.

Coils (laptop off)
PL5 both pins - 181 Ohm
PL6 both pins - about 60k Ohm
PL7 both pins - 29 Ohm
PL8 both pins - 2,9 Ohm
PL9 both pins - 2,9 Ohm
PL10 both pins - 49 Ohm
PL11 both pins - 76 Ohm
PL12 both pins - 76 Ohm
PL13 both pins - 53 Ohm
PL14 both pins - 9k Ohm
PL16 both pins - 41 Ohm
PL17 both pins - 133 Ohm

(Laptop off)
PU2 pin 13 - 3,35V

(Laptop on)
if i made a good measurement pin 114 of KBC chip is 3,35V

tomaszpo ha scritto:PL17 both pins - 133 Ohm

This resistance seems too low.
Check, if this measurement is correct. If so, remove the coil PL17 from the board and measure the resistances to ground on both pins of this coil.

matic ha scritto:

tomaszpo ha scritto:PL17 both pins - 133 Ohm

This resistance seems too low.
Check, if this measurement is correct. If so, remove the coil PL17 from the board and measure the resistances to ground on both pins of this coil.

Sorry my mistake PL17 - 15,2k Ohm and PL16 - 35 Ohm

Measure the power consumption (in mA) of the board before and after pressing to the power button.

matic ha scritto:Measure the power consumption (in mA) of the board before and after pressing to the power button.

If I made a good measurement before pressing power button is 5,64mA and after pressing is about 1,80A.

Measure the power consumption of the board for a short time, when the machine is turned on with disconnected RAM memory.

matic ha scritto:Measure the power consumption of the board for a short time, when the machine is turned on with disconnected RAM memory.

I tried to start it several times and once it was maximum 2.23A, most often around 1.5A

Try to diagnostically heat the GPU as described here.

matic ha scritto:Try to diagnostically heat the GPU as described here.

No effect.

Check, if the CPU and GPU gets warm for a short time, when the machine is turned on.

matic ha scritto:Check, if the CPU and GPU gets warm for a short time, when the machine is turned on.

The CPU gets hot, I can't feel the GPU

Measure the voltages to ground on pins 4, 5, 6, 11, 13, 18, 19, 20 of chip PU7 for a short time, when the machine is turned on.

matic ha scritto:Measure the voltages to ground on pins 4, 5, 6, 11, 13, 18, 19, 20 of chip PU7 for a short time, when the machine is turned on.

PU7
4 - 3,38V
5 - 0V
6 - 0,3V
11 - 0,3 V
13 - 0,28V
18 - 5,08V
19 - 5,08V
20 - 2,08V

Have you counted the pins of chip PU7 correctly?
They should be count as in the following picture.

matic ha scritto:Have you counted the pins of chip PU7 correctly?
They should be count as in the following picture.
[ Obrazek ]

I think now is good

PU7
4 - 2,4V
5 - 3,38V
6 - 1,68V
11 - 2 V
13 - 0,6V
18 - 5,09V
19 - 5,07V
20 - 5,08V

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.