Y50-70 turns on, no video, fans dont spin

[costivl]

Hello,

My Lenovo Y50-70 turns on but i have no video, fans dont spin, keyboard lights turns on, no ssd activity.

I removed battery, hdd, rams, bios battery, then pressed power button for 30 sec to drain out all energy, still same thing, i did check both mosfets on power module of the board, pq301 and pq302, i get 20,5V on all pins except one pin that have 8.7V

Any ideas what to check more?

Thank You

[mcplslg123]

Always write the mb markings and link schematic if its already posted in the forum to get better response.

Check voltage on all big grey coils(mention markings of the coil) after turning power on.

Lets find out whats missing and whats coming up.

[costivl]

Hello,

Board model is ZIVY2 LA-B111P
REV: 1A

I will check voltage on the coils you specified!

[costivl]

Withour power button pressed (battery disconnected, only connected to power adapter):

PL302 - 2.6V
PL402 - 3.3V
PL404 - 5.1V
PL502 - 0V
PL702 - 0V
PL1201 - 0V

[costivl]

With power button pressed (battery disconnected, only connected to power adapter):

PL302 - 2.5V
PL402 - 3.3V
PL404 - 5.1V
PL502 - 1.4V
PL702 - 1.1V
PL1201 - 5.1V

[mon2]

Measure the voltage to ground of LCDVDD rail. This the power rail that powers the LCD. We know from PL1201 that the LCD backlight boost circuit is not working since the output voltage = input voltage = 5v1 (should be ~12v).

The LCDVDD regulator @ U11 enables through the signal PCH_ENVDD. If the LCDVDD is not ~3v, then carefully measure the enable pin on U11 to confirm that the LCD is being requested to turn ON.

[costivl]

With power off on U11 i have:

Pin1 - 0V
Pin2 - 0V
Pin3 - 0.06V
Pin4 - 0V
Pin5 - 0V

With power on on U11 i have:

Pin1 - 0V
Pin2 - 0V
Pin3 - 0V
Pin4 - 3.35V
Pin5 - 0V

[costivl]

I found out that all these smd capacitors are short, check image:

Also on PQ501 pin 1 2 3 4 are short, pin 4 should not be short with 1 2 3

[mcplslg123]

You have 1.4v present on PL502 and PQ501 is the high side mosfet of this circuit-so it cant be bad. Are you measuring it while adapter is connected ? Wait for few minutes after disconnecting power and then measure PQ501.

U11,pin4 is the anable pin and its present. Pin5 Should have 3.3V volts present.Are you sure pin5 of U11 is missing voltage?

Check voltage on pin8-9 of U23 after power on. Is 3V present there?

Connect a external usb keyboard and check whether you get numlock key glowing on toggle.

[costivl]

Connected external keyboard, tried on all 3 usb ports, no leds on the keyboard, neither numlock, checked voltage on usb pins, i only have 5.1V on 1 pin, rest 0V

I have 1.4v on PL502 with power on, addpter is connected and working properly, got 20.5V on both channels.

U11 have 3.3v on pin 5 when power is on

U23 have 3.3v on both 8,9 pins

[costivl]

Schematics https://www.badcaps.net/forum/troubl...50-70-la-b111p

[costivl]

Up!

[mcplslg123]

So its not posting,so there cant be any display.
Check what's missing by using Pg58 power sequence of the diagram.