sony vaio PCG-7141L NO POWER

[Romulo]

Hi everyone this is the first time i troubleshoot this motherboard I need help and advise on this I have receive this Sony vaio vgn-ns140e Model no;PCG-7141L and motherboard number; MBX 202 M790 IP-0087J01 REV.1.1 which is NO POWER no led light and battery charge light but there is 19.9 volts on dc. here is the measurement below;

PQ24 PIN 1.19.9V
2. 19.9V
3. 19.9V
4. 4.17V
5. 19.9V
6. 19.9V
7. 19.9V
8. 19.9V
PQ25 PIN 1.19.9V
2. 19.9V
3. 19.9V
4. 19.9V
5. 2.55V
6. 2.55V
7. 2.55V
8. 2.55V

PU1 BQ2475 PIN 1. 3.3V
2. 2.5V
3. 2.5V
4. 2.5V
5.4..17V
6. 1.69V
7. 0.05V
8. 2.82V
9. 0.05V
10. 3.34V
11. 3.34V
12. 1.14V
13. 2.5V
14. 2.5V
15.0.08V
16. 0V
17. 0.14V
18.0.05V
19. 0.05V
20. 0.05V
21.0.05V
22.0.05V
23.0.05V
24.0.05V
25.0.05V
26.0.05V
27.0.05V
28. 19.79V
PU12 the bios chip has voltage on pin3 1.6v, pin 7 2.4v pin 8 2.4v and there is no 3v on power switch

anyone please help me advise what is the culprit on this board please thanks in advance

[mielta]

hi
on pq25 at pin 5678 there must be 19v
check if there is a short to ground
or remove PR9 and check 19v at pin 5678 at pq25

[smali]

check your I/O (KBC) controller..may be it short..check it VCC pin how many voltage it receiving..it must 3.3v on vcc if it is less than 3v and also check with finger 3v/5v driver ic if KBC is short then 3v/5v driver ic will be heatup..

[Romulo]

thanks for the response @mielta i remove PR9 now there is 3.55v on PQ25 PIN 5678 before there is only 2.55v but still not reaching 19v and also notice PL 1 indutor 100 has only reading of 0.5v.and PL2 capacitor have 0voltage any advise please i need help on this

[Romulo]

@smalli there is no short on kbc

[Romulo]

anyone please advise and help on this please I have attached the schematic

[Romulo]

Anyone please help

[Romulo]

Update after i replace pr9 and remove again and test now there is no voltage on pq25 pin5678 and no voltage on the pads of pr9 any help please

[Romulo]

anyone please help me to find the culprit on this.or can anyone share working bios for this ill try to flash bios

[Romulo]

any help on this please

[mielta]

Hi
You must check PQ25 und PU1 inf any Short

best regards

[Romulo]

I already checked pu1 above post is the reading after i remove the Pr 9 there is no voltage on pin 5678 on pq25 and i checked the resistance of pq25 pin 5678 it shows 0.35ohms the same at the pads of pr9 once it remove any advise please

[cyberhack]

PU1 pin 5 is not correct ACDEC should be fixed PD6 could be faulty or the voltage from page 42 AC_OFF.

[mielta]

Hi
Remove the Battery and Powersupply then give 19v at pq25 pin 5678 with
a Labsuply
Check witch piece would be hot.

[mielta]

Hi
Thats also possible what Cyberhack said i had this problem also by an Sony Labtop
After i dissconnet the Biosbattery for a moment
the Machine run again

[cyberhack]

All so look for spillage and yes i have had laptop start after bios battery discharge.

[Romulo]

Thanks for the response guys i checked pd6 you are right cyberhacl it is shorted to the ground @ mielta i cannot inject 19.5v at pq25 pin 5678 cause i dont have psu lab.ill try to change pd6.and also can i change pr9 to R020 cause original is R015 and i dont have spare.

[mielta]

Hi
Please disconnect Biosbatterie and messure PD6 again

[Romulo]

Remove bios battery still only 0.45volts i already change pd 6 and pu1 still there is no voltage on pq25 pin 5678 replace pr 9 still the same there is no 3v on power switch.

[cyberhack]

Convert a pc power supply to use .
http://makezine.com/projects/compute...upply-adapter/
https://www.youtube.com/watch?v=z2oSFpKh_Uw