acer v3-772g

[germamiga]

hello
i have a laptop acer v3-772g with va70hw motherboard
i change mosfet for the power up............
but my power supply turns in short circuit !!! the led blinking on my acer power supply.........

do you have an idea ???

sory for my poor english..........

[meritosari]

Re: acer v3-772g

It seem +AC_BAT_SYS shorted to ground

There are only 2 pieces resistor on these board. the value are 10 miliOhms
The one for +AC_BAT_SYS (+A/D_DOCK_IN_Q_Q), and the other for +BAT (+BAT R).
These part easy to find it which marked R010

You could remove one to isolate the shorted. then identify goes to where is line have the short

Did you have pics with High resolutions, then upload it here

[germamiga]

Re: acer v3-772g

ok i see it !

i test it !

thanks

[germamiga]

Re: acer v3-772g

I removed R010 ..........
more short circuit
but if I give a new R 010 (0.7 ohm) Short Circuit back ..........

[meritosari]

Re: acer v3-772g

I assume you 've removed the resistor then put your DMM on the pad which side the resistor is shorted to ground? Do this without adapter plug in

[germamiga]

Re: acer v3-772g

I do not understand.
I removed the R010
I tested with the adapter and no bliking.
i put a new 010R and I blink

i think it's r8808

did you want i remove r8808 and i put a weld a cable to ground ????

[meritosari]

Re: acer v3-772g

Sorry for my English and make you was confuse

Please Don't test with adapter, till the shorted has gone

We are chasing part that causing shorted. Since the board have no mark, we need do this thing be carefully. we only test or measure with multimeter (DMM/DVM)

did you want i remove r8808 and i put a weld a cable to ground ????

No. I mean after you've removed the resistor, we need to know where point (pad,pin) that connecting to ground (cause it's have short then it's grounded). Do test with your Digital Multi Meter (DMM) in Diode mode or continuity
we need 100% sure the AC_BAT_SYS have no shorted.

I think it's r8808

I think that too.

That best idea is to make photos whole board (top and bottom sides)

[germamiga]

Re: acer v3-772g

i test it quickly

removed r010

in diode mod,

i put the red pin of my DMM to +a/d-dock_in_q_q and black pin to ground................ 2.4 v.............

[germamiga]

Re: acer v3-772g

picture

[meritosari]

Re: acer v3-772g

You didn't measure on other pads of R8808 (R010). if you get value is 0.000v, then this mean is 100% ac_bat_sys have short circuit.

[germamiga]

Re: acer v3-772g

Good evening,
I measured on the other side of r8808 and I 0 v!

so i have a shot circuit ......where ??? bq24735 ?

[meritosari]

Re: acer v3-772g

There are many components that may be the cause short circuits in the path of this ac_bat_sys, not sure 100% just the BQ chip.

https://www.badcaps.net/forum/attach...1&d=1474145129

I made some screenshots that could be help you trying locating short circuits.
Quickly way find the shorted is using PSU which have current limiting and voltage

https://www.badcaps.net/forum/attach...1&d=1474146064

https://www.badcaps.net/forum/attach...1&d=1474146064

Hard to say " can't share the boardview, cause I don't want to break the rule on one "forum" that I registered as membership. (free forum that was need colecting some points to download doc/file).
anyway, I can share just screen shoot:

Tips from Th3_Un1qu3:

Another way of locating shorts (or at least narrowing down on them), is isolating the individual blocks of the board.

It is highly recommended you have a schematic for this. It's very hard (but not impossible) to do this without one. First remove everything from the board. RAM, CPU, Wifi, etc. If it is still shorted, follow:

• Follow the rail that you find shorted on the schematic.
• Look for jumpers and/or inductors connecting that rail to the rest of the circuit. Unsolder jumpers/remove inductors.
• Check which end of the jumper/inductor still shows a short.
• Repeat until you isolate the short to just one block.
• Test MOSFETs on that block.
• If you found shorted ones, replace them.
• Remove all large ceramic caps.
• Short cleared? Congrats. Replace caps, put the inductors back in, resolder the jumpers and you're good to go.

I have just fixed an Acer Aspire 5315 by this method, B+ was short to ground. A large ceramic cap in the battery charger circuit was responsible for the short.

https://www.badcaps.net/forum/showth...locating+short

https://www.badcaps.net/forum/showth...locating+short

[germamiga]

Re: acer v3-772g

hello
thanks for all

i test : removed q 8806...........short power
removed l 8800 short power
removed q 8804/q8805 short power
removed jp 8802 jp 8803 short power


for the moment removed :

q 8806
l 8800
q 8804 q 8805
jp 8802 jp 8803........................

and the power suply is in short circuit

but i don't find c8806 !

[germamiga]

Re: acer v3-772g

i replace bq24735...................same problem

[meritosari]

Re: acer v3-772g

I recommend you to remove CPU, RAM, Wifi card first.

- Try to measure of All big coils to ground (Diode mode)
- Check all HS mosfet if ok
- Give focus on all ceramic capacitors that written in "Comp.txt". Try remove one by one with slide technic, would it be minimize risk lose these capacitors. if you put in other places probably you'll miss it. Capacitor would be change color and little crack if them has broken.
-If short sircuit still in there, only IC PWM has big chance have been shorted (already on .txt)




ps. I give you wrong info about HS mosfet, seem G**gle translate not working properly, LOL.

[germamiga]

Re: acer v3-772g

ok thanks !!

[germamiga]

Re: acer v3-772g

hello i found the problem !

it's q 8300

irfhs 8342..............

i wait the component for test.............

[germamiga]

Re: acer v3-772g

Fantastic !!!

the motherboard is ok !!!

but i have a problem with another motherboard.
when i plug the power supply, the pc boot itself and no display!!!

[highpulse]

Re: acer v3-772g

pc boot itself , there is no CMOS battery or RTC circuit with short onGND . if AMD machine it will not display any image .
if intel bios might be corrupt

[germamiga]

Re: acer v3-772g

it's an intel bios

i test tuesday with another bios