Lenovo Y50-70(no touch) power on but no display

[didutgendut]

hi my laptop display is dead (no image, no backlight, nothing)
when press the power button the keyboard backlight, power light, battery light is on, no hard drive light and the fan spins for a few seconds. also i got a little heat in the heatsink (i guess the source of the heat around PU1102,PU1103,PU1104)
i have tried replacing the ram, harddisk, external display, wiggle lcd cable, reset the power, etc but still no luck..

is there any other sugestion ?
here i attached the board schematic
thanks !

[dspok]

Re: Lenovo Y50-70(no touch) power on but no display

First check all voltages on coils and let us know.

[didutgendut]

Re: Lenovo Y50-70(no touch) power on but no display

should i check the voltage with or without the adapter connected ?

[caspian]

Re: Lenovo Y50-70(no touch) power on but no display

connect the adapter but it would be better to remove the battery.

[didutgendut]

Re: Lenovo Y50-70(no touch) power on but no display

here's the measurement on coils with battery disconnected and adapter connected

PL101 20.5V
PL102 20.5V

PL201 2.4V
PL202 2.4V

PL302 2.4V

PL401 19.9V
PL402 3.3V
PL404 5V

PL501 19.9V
PL502 0V
PL503 19.9V

PL702 0V
PL701 19.9V

PL902 0V
PL903 0V
PL904 0V

PL1102 0V
PL1103 0V
PL1104 0V

PL1201 0V
PL1202 0V

[caspian]

Re: Lenovo Y50-70(no touch) power on but no display

now measure them again after pressing the power button.

[didutgendut]

Re: Lenovo Y50-70(no touch) power on but no display

is it okay powering it on without the heatsink ? because some coils are under the heatsink and when i powered it on, i can feel warm around the heatsink

[caspian]

Re: Lenovo Y50-70(no touch) power on but no display

it is OK without heatsink but you have to measure one coil and turn it off in about 4 seconds.

[didutgendut]

Re: Lenovo Y50-70(no touch) power on but no display

here's the measurement when powered on

PL101 20.5V
PL102 20.5V

PL201 2.4V
PL202 2.4V

PL302 2.3V

PL401 19.6V
PL402 3.3V
PL404 5.1V

PL501 19.6V
PL502 1.5V
PL503 19.6V

PL702 1V
PL701 19.6V

PL902 0.9V
PL903 0.9V
PL904 0.9V

PL1102 1.7V
PL1103 1.7V
PL1104 1.7V

PL1201 5V
PL1202 12.2V

[caspian]

Re: Lenovo Y50-70(no touch) power on but no display

they seem fine.
now measure pins 100-to-115 of KB9022 after powering on.
be careful to turn off in 4 seconds.

[didutgendut]

Re: Lenovo Y50-70(no touch) power on but no display

okay im going to check KB9022 as soon as possible.
one question is it okay if i get a short circuit when checking those pins ? because those pins looks really close to each others, and i only have a standard multitester leads..
anyway thanks for helping me

[caspian]

Re: Lenovo Y50-70(no touch) power on but no display

you have to use needle leads.
if you use standard leads, you make a short and KB9022 may be damaged.
if you do not have needle leads, connect a needle to your standard lead.