Acer m3-581t led flashing

[bollin]

I´ve got an acer m3-581t ultrabook that i got for free from my job. It was sent for warranty repair, but was rejected because of water damage. I have opened it and found some signs of water, but no fried parts. The screen is the only thing I know is good.

The symptoms are when i plug in the charger a blue led keeps flashing with about one second intervals. The Fan spins up during that time, and also the DVD shows some signs of life when the led is lit.

To me that sounds like at least one short. I downloaded a shematic (ma50 is the model of my main board) which gives my loads of information but i don´t know where to start looking.

[bollin]

Re: Acer m3-581t led flashing

The TPS51225C is fried, so i will start with replacing that if i can find a replacement part.

[Francisco.s]

Re: Acer m3-581t led flashing

I´ve got an acer m3-581t ultrabook that i got for free from my job. It was sent for warranty repair, but was rejected because of water damage. I have opened it and found some signs of water, but no fried parts. The screen is the only thing I know is good.

The symptoms are when i plug in the charger a blue led keeps flashing with about one second intervals. The Fan spins up during that time, and also the DVD shows some signs of life when the led is lit.

To me that sounds like at least one short. I downloaded a schematic (ma50 is the model of my main board) which gives my loads of information but i don´t know where to start looking.

Hi bollin, a link to the schematic will be of great help.
Regards.

[bollin]

Re: Acer m3-581t led flashing

Here´s the link to the schematic:



Not the exact one, I have got rev. 2.1 but close enough.

[affan]

Re: Acer m3-581t led flashing

The TPS51225C is fried, so i will start with replacing that if i can find a replacement part.

[Francisco.s]

Re: Acer m3-581t led flashing

The TPS51225C is fried, so i will start with replacing that if i can find a replacement part.

Hope you have good luck with the replacement.
Regards

[bollin]

Re: Acer m3-581t led flashing

Today i got the replacement, and it is all soldered in. I´m just going to let it cool before i test it...

[bollin]

Re: Acer m3-581t led flashing

No change there, so the next suspicious part is the charger ic, a bq24725rgrr according to the schematic, but those numbers does not correspond to what i found on the chip that is on the board. I will report back if i find anything

[bollin]

Re: Acer m3-581t led flashing

I´ve measured some voltages on the bq24725rgrr. They are:

Pin 1: 19.8v
Pin 2: 19.8v
Pin 3: 19.7v
pin 4: 25.1v
pin 5: 0.55v
Pin 6: 2.65v
pin 7: 0.01v
pin 8: 0v
Pin 9: 0v
Pin 10: 0v
pin 11: 3v, dropping to 2.8v
Pin 12: 3v dropping to 2.8v
Pin 13: 3v dropping to 2.8v
Pin 14: 0v
Pin 15: 0v
Pin 16: 5.96v
Pin 17: 5.87v
Pin 18: 3v dopping to 2.8v
Pin 19: 19.57v
Pin 20: 19.57v

I also checked if there are any voltage to the power button, and everything is at 0v now, and the leds won´t even blink anymore.

[bollin]

Re: Acer m3-581t led flashing

After replacing the TPS51225C, i get 0.63 volts on the 3 volt out pin, so there is a short somewhere on the 3 volt rail?

[Tuomo]

Re: Acer m3-581t led flashing

After replacing the TPS51225C, i get 0.63 volts on the 3 volt out pin, so there is a short somewhere on the 3 volt rail?

Can you measure TPS51225C PIN 3, 7, 12, 13.

Then measure resistance to L8101.

[bollin]

Re: Acer m3-581t led flashing

Can you measure TPS51225C PIN 3, 7, 12, 13.

Then measure resistance to L8101.

Pin 3: 0.63 volts, 788 ohms
pin 7: 0 volts, 787 ohms
pin 12: 19.78 volts, infinite
pin 13: 4.56 volts, infinite

[Tuomo]

Re: Acer m3-581t led flashing

Pin 3: 0.63 volts, 788 ohms
pin 7: 0 volts, 787 ohms
pin 12: 19.78 volts, infinite
pin 13: 4.56 volts, infinite

Looks like 3V not works, so I think chip is failed.

[bollin]

Re: Acer m3-581t led flashing

The chip is brand new from TI, and it shows the same voltages on pin 3 as the previous one so i believe it is something else.

[bollin]

Re: Acer m3-581t led flashing

the 25 volts on bq24725rgrr pin 4 (ACDRV) seems very odd, so i will try to replace that next

[Tuomo]

Re: Acer m3-581t led flashing

the 25 volts on bq24725rgrr pin 4 (ACDRV) seems very odd, so i will try to replace that next

This bq24725rgrr PIN 4 OPEN Q8800 and Q8801, so it they are open problem is somewhere elsewhere.

I think you should focus on TPS51225C operating conditions.

[bollin]

Re: Acer m3-581t led flashing

I will desolder it once more and check the pads, I will do the same with bq24725. I also noticed that there is a solder jumper after pin 3 on the tps51225c that i will desolder and check voltages.

[Tuomo]

Re: Acer m3-581t led flashing

I will desolder it once more and check the pads, I will do the same with bq24725. I also noticed that there is a solder jumper after pin 3 on the tps51225c that i will desolder and check voltages.

Ok.

If that not help can this componet JP8107 @ 1MM_OPEN_M1M2 removed?

Then you can be quite sure where problems is.

[bollin]

Re: Acer m3-581t led flashing

Yes, that was what I was referring to earlier. I will check tomorrow and if I don´t get results I will start desoldering parts.

[bollin]

Re: Acer m3-581t led flashing

I´ll order a new tps51225c, I can´t get any good readings from it. There is a short to ground on the 3 volt rail, i checked c8110 and it showed a short. I desoldered it and I got the same readings when I measured the pads only.