Toshiba L855-10P Totally Dead

[grahamw01]

Hi everyone,

I have a Toshiba L855 10P laptop that is completely dead, I am trying to fix it for a friend and i have had some luck on this forum with laptops in the past so I hope you geniuses can help me again

Apparently it just completely died one day and would not turn on, no fans, lights, not even the charging light comes on when its plugged in. I have already tried a new power supply, and I have checked the voltage in to the motherboard and it is receiving 19.5V, I also checked the visible fuses and they seem fine.

The motherboard model is DK10FG-6050A2509901-MB-A02 Rev 2.0.

It has a sticker for InsydeH20 BIOS inside, and the bios chip is a Winbond 25032BVSIG if it helps!

Many Thanks,
Graham

[dj_ricoh]

Re: Toshiba L855-10P Totally Dead

hello again!
if there is no schematic you need to find all the QFN chips and the sio chip
KB controller .
then we can see where the voltage stops.

p.s. photos! not potato photos

[grahamw01]

Re: Toshiba L855-10P Totally Dead

Hello again!

The reason I stated the BIOS chip is because it has the same chip as the last laptop you helped me with (still working fine by the way!) and it had exactly the same symptoms. I don't think he tried to flash the BIOS here though.

I have attached some pictures, I have tested voltages across Q6010, Q6011 and Q6012, I think these are mosfets to do with the power input (TPCA 8065-H), I think 1 of them had 19V and 2 had 3V.. I can't remember if that is correct though. I think U6000 is the chip that controls the power input.

Thanks!
Graham

[dj_ricoh]

Re: Toshiba L855-10P Totally Dead

I will suggest not to continue but I guess you want!

reason why not ,in the first and second pic. you can see the solder released the flux from it.
so uber preheated or the ... my old friend OVEN.

the chase for the oven came bigger when I saw it had a video chip dedicated.

p.s. I was talking about QFN chips find the models and lets find the charging circuit first.

[grahamw01]

Re: Toshiba L855-10P Totally Dead

Yes I oven'd it, I thought maybe just a bad solder joint somewhere

I found this thread with a similar motherboard and similar problems, but this person reversed polarity of the input voltage which is why, not the case here.

https://www.badcaps.net/forum/showthread.php?p=465244

U6000 is the same here, and someone said "AC detect/charger section which is controlled by the IC U6000." This is a QFN model BQ25A, you can see in first attached picture.

Thanks
Graham

[dj_ricoh]

Re: Toshiba L855-10P Totally Dead

Yes I oven'd it, I thought maybe just a bad solder joint somewhere

I found this thread with a similar motherboard and similar problems, but this person reversed polarity of the input voltage which is why, not the case here.

https://www.badcaps.net/forum/showthread.php?p=465244

U6000 is the same here, and someone said "AC detect/charger section which is controlled by the IC U6000." This is a QFN model BQ25A, you can see in first attached picture.

Thanks
Graham

ok!
lets do this
the QFN chip that u6000(I attach a pic)
write down the values and post it; left to right.

[grahamw01]

Re: Toshiba L855-10P Totally Dead

hello!

Here are the voltages for each pin, the only pin i cant test is 18

1. 7 - 7.5
2. 7 - 7.5
3. 7 - 7.5
4. 7 - 7.5
5. 0
6. 2.685
7. 0
8. 0
9. 0
10. 0
11. 3.1
12. 3.1
13. 3.1
14. 0
15. 0
16. 6
17. 5.85
18. -
19. 3.1
20. 19.05

Pins 1-4 cycled between 7V and 7.5V and the rest stayed at the numbers above.

Also FUSE6050 (for battery) is 3.1V if it helps..

Thanks
Graham

[dj_ricoh]

Re: Toshiba L855-10P Totally Dead

something its wrong there on those first 4 pins
find the fets from the jack maybe we can see where is coming from

[atsio]

Re: Toshiba L855-10P Totally Dead

Check resistance to ground on all pins of Q6011

[ktmmotocross]

Re: Toshiba L855-10P Totally Dead

acok is missing so no energy come through. must resolve acok signal

[grahamw01]

Re: Toshiba L855-10P Totally Dead

Hi everyone, thanks for your comments, the 3 mosfets i can see are below with resistances to ground;

Q6010: pins 1-3; 0.58kOhm. pin 4; 0.69kOhm. pins 5-8; 22.7kOhm.
Q6011: pins 1-3; 0.58kOhm. pin 4; 0.69kOhm. pins 5-8; 0.58kOhm.
Q6012: pins 1-3; 5MOhm. pin 4; 15MOhm. pins 5-8; 0.58kOhm

thanks!

[dellxps15]

Re: Toshiba L855-10P Totally Dead

i see a nuvon controller. maybe this laptop got kb bios ?

[khaahk]

Re: Toshiba L855-10P Totally Dead

BQ24725 should pull ACOK high when pin 6 is 2.68V, i think you need to chenge the BQ24725

[grahamw01]

Re: Toshiba L855-10P Totally Dead

so the mosfets are okay with those values?

dellxps15 the bios is insydeH20

khaahk are you sure or could something else be causing the problem on U6000? I would not be so good at changing the QFN :P

thanks!

[dj_ricoh]

Re: Toshiba L855-10P Totally Dead

one thing before changing that QFN chip , charge the battery somewhere and see if it works with only battery!

[dj_ricoh]

Re: Toshiba L855-10P Totally Dead

without schematic its hard!
I will have suggested to power with wires from battery connector :P

[khaahk]

Re: Toshiba L855-10P Totally Dead

one thing before changing that QFN chip , charge the battery somewhere and see if it works with only battery!

If possible do so.

QFN is the most likely failed component. Can't be 100% sure.

[atsio]

Re: Toshiba L855-10P Totally Dead

What is the voltage on all pins of D6000 and D6002?

[grahamw01]

Re: Toshiba L855-10P Totally Dead

wow guys, managed to charge the battery a bit on my ancient Toshiba L350, good job I kept it all these years! The laptop works fine off the battery!! So what does this mean?

atsio - I don't know the pin numbers but;

D6000 top left; flickers between 6.9V and 7.5V. top right; 19.35V. middle bottom; 19.09V

D6002 top left; flickers between 6.9V and 7.8V. top right; 2.69V. middle bottom; flickers between 7.5V and 8.5V.

thanks!

[cyberhack]

Re: Toshiba L855-10P Totally Dead

Hi atsio have you got schematic