Lenovo L520 - Dont Powered

[ak1_2004]

Hello dear

MB : DAGC8EMB8D0 REV.D
When i Powered laptop 0.13 A and turned off.

Reflash bios
Change IO !
Change Chip !

BUT Dont Get Any Change !

if you any idea , please help me !

thanks

[mon2]

Re: Lenovo L520 - Dont Powered

Hi. Have not searched yet but can you post a link to schematics if they are on this forum?

Start with checking the operation of the first mosfets just after the power adapter enters the logic board.

See the in depth sticky notes from @Piernov above this forum postings. The details of how switching power supplies is noted.

What is the history of the laptop? liquid damage? Just stopped working one day?

If no liquid damage then issue could be a bad capacitor or shorted mosfet. We can check for this next.

[SMDFlea]

Re: Lenovo L520 - Dont Powered

Boardview, no schematic - https://www.badcaps.net/forum/showthread.php?p=1082643

[mon2]

Re: Lenovo L520 - Dont Powered

Ok. Thanks @SMDFlea.

@ak1_2004, start with removing all power.

Meter in resistance mode (200 ohms is ok).

Check and post the resistance to ground on each and every large coil.

If you find a very low resistance value (< 10 ohms) then post the location to review which regulator is linked to the inductor.

The other suggestion is review the first group of mosfets that are mated with the incoming dc adapter. They should be checked for shorts.

Meter still in the scale and resistance mode.

Check and post the resistance for each mosfet:

Source & Drain ?
Source & Gate ?
Gate & Drain ?

if there is a very low resistance value on these readings then very likely the mosfet is shorted. Next step is to remove the mosfet off the logic board and perform the same resistance checks again. If the mosfet is still reading low values, then the mosfet should be replaced.

[ak1_2004]

Re: Lenovo L520 - Dont Powered

All Voltage is ok but v.core is 0
PQ36 part . Drain 20v , source 0v
No short circuit found in the circuit