dell n5110 data problem

[doctormasry]

laptop dell n5110
with white lcd changed u4901 now no white screen i see light but no data

steeps
change lcd and connector between mb and lcd no new
chane cpu becouse motherboard is uma
test out lcd on vga port data ok
volt on lcd1
pin 1 . 2 and 3 =19 v present ok
ping 5 = LCD_BRIGHTNESS 3.3 ok
pin 30 . 29 and 28 = 3.3 LCDVDD ok
pin 27 = 3.3 3D3V_S0 ok
pin 26 = 3.3 LCD_TST_C
pin 24 and 25 =3.3v
pin 23 and 22 =1.2 v
any suggestions

[doctormasry]

Re: dell n5110 data problem

no suggestions?

[mon2]

Re: dell n5110 data problem

1) Can you see the video working for this laptop using the HDMI port & external monitor ? This is to confirm the laptop is working ok.

2) Measure & post the voltages on the other LVDS lines.

LVDS interface requires multiple interconnects to drive the display panel.

If any one of the connections is missing, the display will not work.

Double check that the LVDS connector is soldered properly and with no shorts.

[doctormasry]

Re: dell n5110 data problem

laptop working on external monitor good
lvds
pin 1.2.3 = 19v
pin 5 = 3.3
pin 15 = 3.3 v
pin 30.29.28 = 3.3 lcdvdd
pin 26 = 0v LCD_TST_C

[mon2]

Re: dell n5110 data problem

You missed the voltages for the highlighted pins on the LVDS connector. See my earlier post.

[mcplslg123]

Re: dell n5110 data problem

HALL1(Located bottom right corner. Check Voltage Pin2 & Pin4 and update.

[doctormasry]

Re: dell n5110 data problem

HALL1(Located bottom right corner. Check Voltage Pin2 & Pin4 and update.

thanks @mcplslg123
pin 2 is 0v
pin 4and 5 = 3.3 v

[doctormasry]

Re: dell n5110 data problem

You missed the voltages for the highlighted pins on the LVDS connector. See my earlier post.

all measurements are in the picture
thanks

[doctormasry]

Re: dell n5110 data problem

HALL1(Located bottom right corner. Check Voltage Pin2 & Pin4 and update.

I MAKE jumper a wire between pin2 and pin4
but same still backlight ok no data

[mon2]

Re: dell n5110 data problem

Pins 16 & 17 on the LVDS connector are too low for the LVDS connector.

Each is 0v78 ?

Remove the LVDS display and measure the voltage on 16 & 17 again.

Does the voltage change ? Hoping that the video display will still be driven with some signals over LVDS pins even though the display is removed. These pins should be @ 1v2 like the other data lines for the display.

Keep the display removed, do not attach any power -> meter in resistance mode (2k should be ok).

Red meter probe on pad to test; Black meter probe to ground (shield is ok).

Check the resistance to ground on pin #16 of the LVDS connector. Reading ?

Repeat for pin # 17 of the LVDS connector. Reading ?

If the reading is too low then there may be a fault in the trace / shorting to ground.

The schematic shows that there should be nearby caps to ground for each of the LVDS signals, including the pins 16 & 17. Can you find them ? Once they are found, carefully remove them off the PCB as they may be causing this data pair to be lower than the others. Just remove one at first and see if the voltage on the linked pin on the LVDS pin goes higher. Then remove the next one and check again. Perhaps liquid damage / corossion in this area? Worth a review. If no improvement, then place the caps back. See attached.

After the above, it appears that the PCH is the direct video connect to this display. If the display is 100% known good and compatible with this box then it should work but concerned about the pin 16 & 17 voltages being lower than the others.