Acer Aspire 5750 no B+ voltage

[multiplexer]

Re: Acer Aspire 5750 no B+ voltage

the only reason is there is 0.25 v on the gate pins of PQ6 and PQ7.
https://www.badcaps.net/forum/attach...1&d=1410357719

Voltages do not match.
What are the correct values ?

[smali]

Re: Acer Aspire 5750 no B+ voltage

Are you receiving 19v on pin 1(source) of PQ7

[polytek]

Re: Acer Aspire 5750 no B+ voltage

please look at page 56 on schematic diagram, it s design fault by compal.

[ahmetozay]

Re: Acer Aspire 5750 no B+ voltage

before it was 19v on all pins of PQ6 and 19v on 1-2-3-4 of pins of PQ7 but 1v output. Measured PU1 of pin 8 and it was 0v which means vref is 0v thus i changed PU1 and vref is 2.4v now but there is 0.2v on the gates of PQ6 and PQ7 now.

if i connect 19v from PQ6 to PQ7 output the system works without battery( i canot connect battery because it will short circuit)

So far...
1- changed PU1(vref is 2.4v now)
2- changed PQ6 and PQ7
3- flashed KBC and Main bios

[atsio]

Re: Acer Aspire 5750 no B+ voltage

Replace the fets of the charger

[ahmetozay]

Re: Acer Aspire 5750 no B+ voltage

Replace the fets of the charger

just changed two fets and the situation is same. Someone pls can explain me the protection circuit at page 48 in the chematics. why 0.2v at the gates of PQ6 and PQ7? i checked all components removed resistors and measured them. Changed 2 times of PU1 charging circuit. Changed fets of PU1, changed PQ6 and PQ7. even flashed both roms. there is nothing shorted on the board i am sure because if i apply 19v to the output of PQ7 board works perfect. Very strange!!!

[multiplexer]

Re: Acer Aspire 5750 no B+ voltage

PQ14
1=0v
2=0v
3=0v
4=0v
5=0v
6=6.1v

Confirm these measures?
If confirmed replace PQ14 (already recommended)

Another test to confirm PQ14 failure:
Unsolder PQ10 and measure the voltage on pin 4 of PQ7 is 8V

[multiplexer]

Re: Acer Aspire 5750 no B+ voltage

Correct values to detect:

[ahmetozay]

Re: Acer Aspire 5750 no B+ voltage

Correct values to detect:

definitely the problem is not in the protection circuit. If i short the legs PQ6 to PQ7 for 19v i get the corect values on all parts in the picture. So something differentmust be blocking 19v at the gates. i mentioned before when i turn on the power the voltage rises slowly upto 0.8v and after turn off the power drops slowly down to 0v. So i guess something and most probably a capacitor is faulty and gets charged slowly and de-charges slowly. What is your opinion?


PS. i removed PQ10 and there was no 8v instead same 0.2v

[multiplexer]

Re: Acer Aspire 5750 no B+ voltage

if i apply 19v to the output of PQ7 board works perfect. Very strange!!!

On pin 5-6-7-8?
With voltage values as my design
Check PC12, PC7, PR17, PR27
Others can not be broken.

[smali]

Re: Acer Aspire 5750 no B+ voltage

You must receiving 19v on pq6 source if not then confirm the channal of replaced mosfet..when you reveived 19v on both souce of pq6&7 and no outputs on pq7 drain so check pq8 (PNP Transistor ) and pq10 (NPN ). And for checking short the collector and emmiter of the PQ10 and ckeck out put voltage on pq7 (drain ) but before you must received 19 volt on both combined sources of pq6&7.

[multiplexer]

Re: Acer Aspire 5750 no B+ voltage

Fix your measurements with the design

[cyberhack]

Re: Acer Aspire 5750 no B+ voltage

Reading all the posts some times one must do a blanket repair. Replacing all the
semi conductors in the area in one go,could be tolerances out.

[spidey]

Re: Acer Aspire 5750 no B+ voltage

hi, acording the first post (at the moment dont have time to read whole threads) it look like the protection circuit somehow in a fault mode. i would search for a short, ecpecially on charging circuit and standby circuit. if you short b+ to adapter voltage then if the system is working; stanby, EC, bios, cpu and graphics vcore and clockchip is ok, then check usb ports, componentes attached to usb port(web cam, card reader etc.), charging circuit. i'll read whole posts and next time i come back try to help you more. seems like a bad cap.

[ahmetozay]

Re: Acer Aspire 5750 no B+ voltage

hi, pins of PQ6 and PQ7 shorted and disabled battery. Delivered to customer working only with ac adapter. End of the story. Thanks for all your help

[kalimuthu]

Re: Acer Aspire 5750 no B+ voltage

Check your super i/o controller.

[highpulse]

Re: Acer Aspire 5750 no B+ voltage

well i got a 5750g , with the la-6901p motherboard and i got a weird issue happening .
This one client complain machine is turning on then off . i noticed that it does that but then turn on alone and stay on ..
the main thing i notice is that , if it works only with dc power , or only with battery , turn on and stay on .
if i insert both , then it turn on then off , then it will turn on and give image..
another thing i notice , when i plug dc and battery , and dont turn on , just to see how its charging , well it does start ok , increasing amp consume . when achieve is higher value , then the amp consume stay crazy , drop from 1.5 amp to 0 then 0.8 1,4 1.7 . 0.8 0 etc and thats not usual , cheked main fets , pq 15 pq 16 pq5 pq7 pq6 pq14 and all seem fine , i even replaced just in case the bloody charger isl6251 but still the same .
strange , any opinions?

[highpulse]

Re: Acer Aspire 5750 no B+ voltage

insyde windows , well its seem charging the battery as it should , as also when charger the blue light will turn on , indicating battery is full ...