Lenovo Y50-70 - LA-B111P Rev:1A Flickering laptop screen after shorten the R205 resistor/ backlight restoration ?

[EffiSon]

Hi. Could anyone on the forum help me find the cause of the problem?
The board is LA-B111P Rev:1A comes from Lenovo Y50-70.

I have a identified the damaged R205 resistor, and connect a jump wire over it So it restores the backlight but causing strange problems

1. With Battery ONLY plugged in laptop works fine
2 .With Charger ONLY plugged in laptop works fine as well

3. Connecting both battery and charger at the same time shows a strange flickering screen. The flickering is not constant, it is completely random (and I think it depends on the load of the motherboard's power supply)

Any suggestions or help would be appreciated

[mon2]

Was R205 ever on this board? The component is marked with a '@' symbol in the schematic which means it is a 'no stuff' on the PCB. The power path for this rail is through R375. Do you have a proper voltage without this R205 bypass? If not, review the EMI filter from the other partial schematic you have posted. Is that filter damaged or still ok? Without any power -> meter in resistance mode -> measure the resistance across this filter / coil. It should be ~0 ohms. If it is not, it should be replaced or can be bridged (if in a pinch).

[EffiSon]

Was R205 ever on this board? The component is marked with a '@' symbol in the schematic which means it is a 'no stuff' on the PCB. The power path for this rail is through R375. Do you have a proper voltage without this R205 bypass? If not, review the EMI filter from the other partial schematic you have posted. Is that filter damaged or still ok? Without any power -> meter in resistance mode -> measure the resistance across this filter / coil. It should be ~0 ohms. If it is not, it should be replaced or can be bridged (if in a pinch).

Thanks for the quick response, it was my bad i wrote the wrong component designator it was R375 which was open/damaged.
I have not tested the entire filter blocks but was checking capacitors which were not short to ground atleast.

Two more strange things i found was on the display connector
1. JEDP1 has missing pins 39, 38 & 37 (39 & 38 are the same INVPWR_B+ pin where as pin 37 is GND)
but not sure if that is the reason of the noise to the LCD backlight ? or 1 INVPWR B+ pin connection is sufficiant ?
similarly there are multiple GND pins so pin 37 shall not be a problem but do you think that is also one of the reson to have that problem ?

2. LVDS connector which connects on laptop motherboard also has some burnt marks and missing the same pin as above, do not know the root cause !!!

But on top of all these broken parts why the laptop works without problem with either on Battery or on Charger ?