Toshiba Laptop L855 dead and not charging

[laz1234]

Hello everyone, my laptop went totally dead and the battery is not charging. My power adapter works fine and i am getting 19V input on MB.

Motherboard is DK10FG-6050A2509901-MB-A02

I replaced Q6010, Q6011 and Q6012, but i had no changes.

Schematics (Power circuit is at page 5):
View attachment Toshiba Satellite C850 C855 - INVENTEC DAKAR10F DAKAR10FG - 6050A2491301-MB-A02 MP - 20120323.pdf

Measurements on U6000:


U6000 datasheet:
View attachment bq24725a.pdf

M/B:


Any suggestions?

 

[pplus]

ACDET is low - 1.24V

8.4.1 Adapter Detect and ACOK Output
The bq24725A uses an ACOK comparator to determine the source of power on VCC pin, either from the battery
or adapter. An external resistor voltage divider attenuates the adapter voltage before it goes to ACDET. The
adapter detect threshold should typically be programmed to a value greater than the maximum battery voltage,
but lower than the maximum allowed adapter voltage.
The open drain ACOK output requires external pull up resistor to system digital rail for a high level. It can be
pulled to external rail under the following conditions:
• VVCC > UVLO;
• 2.4V < V_ACDET < 3.15V (not in ACOVP condition, nor in low input voltage condition);
• VVCC–VSRN > 275mV (not in sleep mode);

 

[laz1234]

ACDET is low - 1.24V

Thanks a lot for the answer, yes I' ve noticed it, but i cannot explain why. Do you have any idea? I measured R6002 and it is 20K. Maybe capacitor C6029 is short-circuited? Any other suggestion?

 

[pplus]

Worst case - burned input transistor of comparator U6000 . Other cases - leak C6029, changed resistance R6002, R6003.

 

[laz1234]

C6029 does not seem to exist on board. I searched again and again. I measured the resistors and found the correct values. So shall i go for the U6000?

 

[pplus]

R6003 marked as 516 - 51M, it's right?


- - - Updated - - -

Carefully cut wire to pin 6 U6000 and check again.

 

[laz1234]

pplus yes the R6003 is as marked. But C6029 is empty (just solder). I thought about cutting the pin6 or partially unsolder R6003 but they are so tiny I could destroy something. I ordered a new U6000 and i will post the results.