Lenovo G480(LG4858L 11326) Power problem

[YourLocalGeek]

hi guys

lenovo g480
MB CODE: LG4858L MB 11326-1

laptop turns on (automatically) only if cmos battery has been reseated.
after shutdown, laptop does NOT turn on using power switch
cmos battery has to be reseated again for it to turn on.


any ideas?
thanks in advance

attached are the schematics
please help

[ktmmotocross]

Re: Lenovo G480(LG4858L 11326) Power problem

check if u can start the board without attached power switch board. looks like your power button is not working

[YourLocalGeek]

Re: Lenovo G480(LG4858L 11326) Power problem

thanks for the reply ktm
but sorry board still wont turn on without power switch i tried switching it on by shorting pin 2(kbc_pwrbtn) to ground of btncn1 (power switch board port) or am i doing it wrong?

[ktmmotocross]

Re: Lenovo G480(LG4858L 11326) Power problem

try to short KBC_PWRBTN_EC# on C2717 and check voltage on it

[YourLocalGeek]

Re: Lenovo G480(LG4858L 11326) Power problem

same results boss still wont turn on
voltage on c2717 is 1.11v

is the kbc faulty?

[ktmmotocross]

Re: Lenovo G480(LG4858L 11326) Power problem

check both sides of R2703 and R2704 for voltage

[YourLocalGeek]

Re: Lenovo G480(LG4858L 11326) Power problem

R2703 1.11V both sides
R2704 1.11v & 3.3v other side
is that good?
again thanks for the time ktm

[ktmmotocross]

Re: Lenovo G480(LG4858L 11326) Power problem

1.1V is low. it must be 3V. check resistance of R2774 and R2704

when nothing try to remove EL8204.

all this things do with powerswitch board removed

[YourLocalGeek]

Re: Lenovo G480(LG4858L 11326) Power problem

in circuit resistance
R2704: 9k
R2774: 13k

and then i removed el8204
same resistance but voltage changed from 1.1v to 3v

tested it out of circuit
r2704: 10k
r2774: 99.6k

[ktmmotocross]

Re: Lenovo G480(LG4858L 11326) Power problem

ok,, u have 3V. so now try to start it by shorting KBC_PWRBTN_EC# on C2717 to ground

[YourLocalGeek]

Re: Lenovo G480(LG4858L 11326) Power problem

tried shorting c2717 to ground
mboard turned on for 1 sec then turns off?
it looks like i can switch it on now but now it turns off after 1 sec

tried it without cmos battery and i turned it off (after it automatically turned on) and tried switching it on again, it turns on and off after 1 sec
but for the 5th time mboard stays on

[ktmmotocross]

Re: Lenovo G480(LG4858L 11326) Power problem

ok. so leave removed that coil and try to switch on with powerswitch board.

for that 1s switching check power sequence at the end of schematic

[YourLocalGeek]

Re: Lenovo G480(LG4858L 11326) Power problem

thank you ktmmotocross for your time and guidance
laptop works great now

for the 1s switching, i just assembled the laptop (i think its because there was no cpu before) and it worked with just 1 press to turn it on.

thanks again boss
more power to badcaps and to ktmmotocross

[mcoytzhi27]

Re: Lenovo G480(LG4858L 11326) Power problem

any dump files for this unit.. thanks...

[andrew25]

Re: Lenovo G480(LG4858L 11326) Power problem

need bios dump too for it

[andrew25]

Re: Lenovo G480(LG4858L 11326) Power problem

need bios dump too for it

[Homero]

Re: Lenovo G480(LG4858L 11326) Power problem

hi guys

lenovo g480
MB CODE: LG4858L MB 11326-1

laptop turns on (automatically) only if cmos battery has been reseated.
after shutdown, laptop does NOT turn on using power switch
cmos battery has to be reseated again for it to turn on.


any ideas?
thanks in advance

attached are the schematics
please help

try reprogramming the BIOS. I leave the link here:
https://mega.nz/#!2R9CnSLL!PJJugfreu...tgyi83gBmvNds0