LENOVO G580 no power

[mo000]

hi
lenovo g580 LA-7981p dead no power no led
3.3/5v is missing
IC POWER RT8205
vin 19v
en 3v
vreg5 5v
vreg3 3v
entrip1 0.6v
entrip2 1.2v
pgood 0v
no short on 3.3/5 lines

is that means the kbc is defective ? .

[mon2]

Re: LENOVO G580 no power

Remove all power. Meter in resistance mode (2k scale is ok).

Check and post the resistance for each mosfet linked to these rails:

source (1-2-3) & drain (5-6-7-8)
source (1-2-3) & gate (4)
gate (4) & drain (5-6-7-8)

Check mosfets PQ401, PQ403, PQ402, PQ404.

Next check the gate voltage of each mosfet. Is this regulator even putting out any gate voltage ?

Is B+ voltage present on the high side mosfets ?

Personally do not know but how is KBC linked to this switching regulator?

Looks like that PU401 is defective but share the above details.

[mcplslg123]

Re: LENOVO G580 no power

What is the consumption on your dc supply??

[mo000]

Re: LENOVO G580 no power

what is the consumption on your dc supply??

0

[mo000]

Re: LENOVO G580 no power

Remove all power. Meter in resistance mode (2k scale is ok).

Check and post the resistance for each mosfet linked to these rails:

source (1-2-3) & drain (5-6-7-8)
source (1-2-3) & gate (4)
gate (4) & drain (5-6-7-8)

Check mosfets PQ401, PQ403, PQ402, PQ404.

Next check the gate voltage of each mosfet. Is this regulator even putting out any gate voltage ?

Is B+ voltage present on the high side mosfets ?

Personally do not know but how is KBC linked to this switching regulator?

Looks like that PU401 is defective but share the above details.

all resistance no reading except (S-G) OF PQ401 and 402 shows 0ohm
the two mosfets are ok but i change them but same results .
gate voltage of each mosfet 0v
yes b+ present on high mosfets
.

[mcplslg123]

Re: LENOVO G580 no power

is +19V reaching CLR?? I think not as consumption is "0" on dc supply.

[mo000]

Re: LENOVO G580 no power

is +19V reaching CLR?? I think not as consumption is "0" on dc supply.

yes the consumption is 0
and +19v reach to power ic and both high mosfets
main power rail is ok and no short .

[mcplslg123]

Re: LENOVO G580 no power

@mo000, be specific in your replies as mb is not in our hand. Which power ic and high side mosfets you are talking about?? Why not check on CLR??

[mo000]

Re: LENOVO G580 no power

@mo000, be specific in your replies as mb is not in our hand. Which power ic and high side mosfets you are talking about?? Why not check on CLR??

i talk about 3.3/5v power ic PU402

which CLR you mean ?
you mean PR302 .

[mo000]

Re: LENOVO G580 no power

any idea ?

[mcplslg123]

Re: LENOVO G580 no power

Yes PR302 but +19v is likely there as it reaches PU402. You should focus on charging IC as dc-in mosfets gates are not opening. So if +19V reaching CLR , your mosfet is working in diode mode without proper biasing. This needs to be fixed first. Improper +19V entrance to mb can cause many problems. Give us measurements on charging ic.

[mo000]

Re: LENOVO G580 no power

Yes PR302 but +19v is likely there as it reaches PU402. You should focus on charging IC as dc-in mosfets gates are not opening. So if +19V reaching CLR , your mosfet is working in diode mode without proper biasing. This needs to be fixed first. Improper +19V entrance to mb can cause many problems. Give us measurements on charging ic.

cahrger ic BQ737

pin1 +19v
pin2 19
pin3 0
pin4 0
pin5 0
pin6 2.7
pin7 0
pin8 0
pin9 0
pin10 0
pin11 0
pin12 19
pin13 19
pin14 0
pin15 0
pin16 6
pin17 18.9
pin18 19
pin19 19
pin20 19

[mcplslg123]

Re: LENOVO G580 no power

Going by the charging ic readings,problem is absence of 3v ldo but you said 3vreg is present. Are u sure 3v reg(ldo) is present?? U don't have sda/scl on charging ic and neither acok is there on pin5 which pulls the voltage from 3v ldo. So check again 3v reg is present or not. Btw, VFB1/vfb2 voltage on 3-5 v regulator??

[mo000]

Re: LENOVO G580 no power

Going by the charging ic readings,problem is absence of 3v ldo but you said 3vreg is present. Are u sure 3v reg(ldo) is present?? U don't have sda/scl on charging ic and neither acok is there on pin5 which pulls the voltage from 3v ldo. So check again 3v reg is present or not. Btw, VFB1/vfb2 voltage on 3-5 v regulator??

yes 3vreg is present (pin8 rt8205e)
vfb1/fb2=0v .
this laptop drop me to insane .

[mon2]

Re: LENOVO G580 no power

Your +3VALWP rail appears to be absent. This rail defines the SMBUS pull-up resistor. Since the reading is 0 volts on SMBUS, most likely the pull-up resistors are not being pulled up to 3v3. Issue is with PU401 who generates the +3VALWP rail.

Check and post the voltages for the attached points for PU401.

Has PU401 been replaced before ?

[mo000]

Re: LENOVO G580 no power

Your +3VALWP rail appears to be absent. This rail defines the SMBUS pull-up resistor. Since the reading is 0 volts on SMBUS, most likely the pull-up resistors are not being pulled up to 3v3. Issue is with PU401 who generates the +3VALWP rail.

Check and post the voltages for the attached points for PU401.

Has PU401 been replaced before ?

the readings in attachment .
why pu401 has all the requirement voltages but can't generate 3.3/5v ALW?
btw i try to replace it but same results .

[mon2]

Re: LENOVO G580 no power

There are different versions of the RT8205 part (PU401). The full part number is very important.

Do you have the original part still available ?

Post the pic / markings of the original part.

What are the markings of the replacement part on the board ?

The part number you must use is:

RT8205EGQW

Top markings are 'DT='

https://www.aliexpress.com/item/4001...rch-mainSearch

[mo000]

Re: LENOVO G580 no power

There are different versions of the RT8205 part (PU401). The full part number is very important.

Do you have the original part still available ?

Post the pic / markings of the original part.

What are the markings of the replacement part on the board ?

The part number you must use is:

RT8205EGQW

Top markings are 'DT='

https://www.aliexpress.com/item/4001...rch-mainSearch

I use TPS51225

[mon2]

Re: LENOVO G580 no power

RT8205EGQW = 24 pin device + 1 pin for the center bottom ground pin.

TPS51225 = 20 pin device + 1 pin for the center bottom ground pin.

Unless you have a different version of the TPS51225, they are not pin for pin compatible.

[mo000]

Re: LENOVO G580 no power

RT8205EGQW = 24 pin device + 1 pin for the center bottom ground pin.

TPS51225 = 20 pin device + 1 pin for the center bottom ground pin.

Unless you have a different version of the TPS51225, they are not pin for pin compatible.

yes it's 24 pin
The part number of the original is EM FA
I also repace it with another ic withe part number EM FB
but same result
I think after all the problem in kbc .