Acer Aspire 5740g dead (no power - no lights)

[RJARRRPCGP]

Re: Acer Aspire 5740g dead (no power - no lights)

More info: http://www.laptopdesktopschematic.com/

This site demands payment for downloads. Avoid.

[spleenharvester]

Re: Acer Aspire 5740g dead (no power - no lights)

Just had an idea occur to me reading through this thread. Pretty impressive diagnosis of a faulty MOSFET. It's made me realise - we see an awful lot of failed repair attempts on here, that's just the nature of board level repair. But is it worth compiling a big list of success stories that people have had like this one? That way, if someone comes on with an identical problem, they can look it up.

[oxonater]

Re: Acer Aspire 5740g dead (no power - no lights)

Hi thanks for the reply hmm I'm stumped I did look at the dc jack gave it a touch of solder (in case of dry joints) and it appeared to power on. Then started to put it back together then it was back to not working, not sure if pressing down on board a little whilst putting back together may have done something. I believe this board is the same in a Advent K3000. Where could I start with the testing power circuit thanks in advance Kris.

[bgaservis]

Re: Acer Aspire 5740g dead (no power - no lights)

Today I have fixed one with this same symptoms, eg dead, no 3.3V no 5V.
Checked supply of the TPS51123 everything ok, but no S5 enable, ok move next to SIO.
Supply is ok, but there is no RSMRST, next checked with scope U16 EC bios chip, no comunication, removed bios chip, reprogrammed it, checked with scope, it's working, power button everything ok, problem solved

[fddizon]

Re: Acer Aspire 5740g dead (no power - no lights)

if no S5_enable and SIO supply are present,

go directly to BIOS chip. replace or reprogram

[dj_ricoh]

Re: Acer Aspire 5740g dead (no power - no lights)

if no S5_enable and SIO supply are present,

go directly to BIOS chip. replace or reprogram

sry for the dumb Q SIO supply values are represented by?

i know i know its a stupid Q but maybe its general Q.
don`t judge plzz

[bgaservis]

Re: Acer Aspire 5740g dead (no power - no lights)

SIO 3D3V_AUX_S5 supply comes from TPS51123 pin no. 8.

[dj_ricoh]

Re: Acer Aspire 5740g dead (no power - no lights)

vreg refer to S zone. like vreg1.. vreg3
aham ty

[tomodachi]

Re: Acer Aspire 5740g dead (no power - no lights)

I have an Acer Aspire 5740g with no power - no lights . Adapter is tested ok , motherboard is getting power 19V from power jack . I've found some mosfets getting 19V also and one with 3.3V but nothing else (nowhere 5V , or 1.1V) .Also , I can see 3.3V on the power button but nothing on LEDs . Any help please where to look ?

Same case happened to me 2 weeks ago, I have managed to fix it reflashing the eprom near to KBC I can't remember location code but it has smaller size than BIOS, and you can find its dump file at acer official support.
Good luck.

[adrianharris]

Re: Acer Aspire 5740g dead (no power - no lights)

You probably need to flash KBC BIOS, I had same symptoms: Acer Aspire 5740G: how to flash KBC BIOS (reasons - no power, doesn't charge, no LED)

[Th3_uN1Qu3]

Re: Acer Aspire 5740g dead (no power - no lights)

I have got the laptop fixed after replaced U72 and re-programmed BIOS (U16).

Another one here. This is the 5740 model, with i3 CPU and intel integrated graphics. It was completely dead. Found no output from main 3.3v and 5v rails, although the LDOs worked. Replaced U72 TPS51123 and it lights up and spins the fan for a bit, however it doesn't do anything else.

Pulled the BIOS chip and reprogrammed it, it failed verification. Replaced with a NEW pre-programmed BIOS chip, and it still does the same thing. Lights, fan spins and then stops and that's it. All voltages ok. Any other ideas?

[seliarizwan]

Re: Acer Aspire 5740g dead (no power - no lights)

[QUOTE=Th3_uN1Qu3;409996]Another one here. This is the 5740 model, with i3 CPU and intel integrated graphics. It was completely dead. Found no output from main 3.3v and 5v rails, although the LDOs worked.

Pulled the kbc BIOS chip and reprogrammed it, power led blink after 5 sec interval any solution

[cyberhack]

Re: Acer Aspire 5740g dead (no power - no lights)

Can you upload the file you used

[seliarizwan]

Re: Acer Aspire 5740g dead (no power - no lights)

Here's the KBC bios

[nero80]

Re: Acer Aspire 5740g dead (no power - no lights)

Acer Aspire 5740G KBC BIOS Dump

[anuragis1]

Re: Acer Aspire 5740g dead (no power - no lights)

I have a same problem , laptop is appearing to be fully dead. So , I checked and found the smd chip choke coil/power inductor near cpu is burnt and is shorted. It is marked as 'R44' in schematic pdf ,which is acer part no. 68.4R710.10G .Can anbody please tell description/specification of this component.

[seliarizwan]

Re: Acer Aspire 5740g dead (no power - no lights)

R44 is a register with value 4.7 ohm

[dellxps15]

Re: Acer Aspire 5740g dead (no power - no lights)

fixed a dead 5740g today. no charging, no light. checked pin 16 of u72 and got 19volt. checked pin 18 (s5 enable) and was 0 volt. checked pin 8 and was 3.3 volt, so reprogrammed kb bios and now is working fine.

[storexxm]

Re: Acer Aspire 5740g dead (no power - no lights)

Hello to all electronic specialists-
I got an aspire 5740. It stays complete dead when plugging in the psu.
Another thing is the psu light goes off when pluggin in and get back when replug vom power. So it seems to be shorted. Could this be also a problem with the BIOS ?
Please if somebody can help-
Greetings from austria.
Alex

Additional i found this...
anybody else who got the same issue ?

My Acer Aspire 5740G is not starting. Adapter light goes off after connecting to laptop. So, I checked the motherboard JV50-CP 09285-1M 48.4GD01.01M and I found a short near CPU, it is marked R44 --> 68.4R710.10G which is a SMD power inductor/chip choke coil. Can anybody identify the part's name/specifications?

[dellxps15]

Re: Acer Aspire 5740g dead (no power - no lights)

for shorted coil what value u have ? in diode mode, a short is 001 002. if it's 010 it's not short but is low impegance given from the chip itself.

if u have short in cpu, remove cpu and try another one (if short disapperared withoud the cpu inserted).

but you say psu light go off as soon as u insert it in to jack. so i assume short is not in cpu rail, but in power startup sequenze... from 19 to 3.3 and 5 volt regulator.

cpu volt is after that part, and should turn off psu asfter power swith is pressed.