Acer Aspire 5750 no B+ voltage

[multiplexer]

Re: Acer Aspire 5750 no B+ voltage

correct values

[ahmetozay]

Re: Acer Aspire 5750 no B+ voltage

correct values

my measurements as follow

[ahmetozay]

Re: Acer Aspire 5750 no B+ voltage

correct values

Better to put this way

[ktmmotocross]

Re: Acer Aspire 5750 no B+ voltage

pq17 must be shorted or acoff is on.

have one of these with bad pq17

[multiplexer]

Re: Acer Aspire 5750 no B+ voltage

Possible faults:
ACOFF incorrect value
PQ17 short between the collector and emitter
PQ14 short between pins 1-2 and 4-5

[ahmetozay]

Re: Acer Aspire 5750 no B+ voltage

No shorts on PQ17 or PQ14. there is only one option left i think and it is ACOFF . I assume ACOFF comes from KBC so do you advice to change it or there is a way to test it.

PS. if shorted pin 1 and 8 of PQ7 the system works without battery fine if i insert battery and short the pins of PQ7 short occures on Power supply.

i have not tested with the battery beause battery is empty and i dont have other one

[multiplexer]

Re: Acer Aspire 5750 no B+ voltage

Measure the voltage on ACOFF PQ17
Desolders PQ17 if your laptop is running (no short on 1-8 FP7) program bios U36, U38

[ahmetozay]

Re: Acer Aspire 5750 no B+ voltage

Measure the voltage on ACOFF PQ17
Desolders PQ17 if your laptop is running (no short on 1-8 FP7) program bios U36, U38

ACOFF is 0v
removed PQ17 but no start
now flashing U36 and U38 then write the result here

flashed both kbc and main but the result is same.
there is one odd situation when i turn on the power the output of PQ7 rises slowly upto 0.8v and when i turn off the power the output drops down slowly to 0v. i took a video and share the youtube link soon.

[multiplexer]

Re: Acer Aspire 5750 no B+ voltage

PR38 fails
replace

[multiplexer]

Re: Acer Aspire 5750 no B+ voltage

Please attach your schema compare if it is equal to my

[ahmetozay]

Re: Acer Aspire 5750 no B+ voltage

Please attach your schema compare if it is equal to my

here it is

[ahmetozay]

Re: Acer Aspire 5750 no B+ voltage

Here is the youtube link http://youtu.be/B78hyYI4xUg

[ahmetozay]

Re: Acer Aspire 5750 no B+ voltage

PR38 fails
replace

removed PR38 and measured 47k as stated in the schema so PR38 is ok

[multiplexer]

Re: Acer Aspire 5750 no B+ voltage

My schematic is rev 0.1
I confirm check PR38 = 47K ohm
Thanks for the schematic

[ahmetozay]

Re: Acer Aspire 5750 no B+ voltage

My schematic is rev 0.1
I confirm check PR38 = 47K ohm
Thanks for the schematic

PR38 is ok 47K ohm measured

[multiplexer]

Re: Acer Aspire 5750 no B+ voltage

Thanks for the reply

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

Measure the voltages on all the pins of Q8, Q10, Q14
If you confirm these measures failure PQ14. Replace it

[smali]

Re: Acer Aspire 5750 no B+ voltage

Have you checked PQ6?
checked the drain and source short.

[polytek]

Re: Acer Aspire 5750 no B+ voltage

looks like ocp problem, Replace with the correct mosfet 4459, to be sure, remove PR14 and mesure again if you find 19V on PQ7 drain, please replace with the same reference;

[smali]

Re: Acer Aspire 5750 no B+ voltage

Checked PQ6 if it is short then 19v will comes to PQ7 gate and this FET will be closed and no output voltage to onward circuit so checked and repalced PQ6.

[ahmetozay]

Re: Acer Aspire 5750 no B+ voltage

Checked PQ6 if it is short then 19v will comes to PQ7 gate and this FET will be closed and no output voltage to onward circuit so checked and repalced PQ6.

well already checked and replaced nothing wrong there.i am stuck really.
if i short pin 8 of PQ6 with pin of PQ7 system works without battery. the only reason is there is 0.25 v on the gate pins of PQ6 and PQ7.