Laptop Dell Inspiron 15, 5570, LCD issue

[suiramix]

Laptop Dell Inspiron 15, 5570, LCD panel damaged, no backlight, external monitor attached works fine… removed LCD and the 30 pin connector was burned at +BL_PWR. Replaced with new display cable and brand new (similar) LCD panel but same issue. Run the Dell diagnostic test and get the error “LCD cable not connected “. No visible burned components on MB (fuse F1 is ok). Checked the voltage at motherboard eDP connector found the +19VB rail (+DCBAT_LCD) is only 13.1V powered on charger or battery. Is that normal?

[mcplslg123]

Re: Laptop Dell Inspiron 15, 5570, LCD issue

13.1V is normal as this mb works on +13V.

[suiramix]

Re: Laptop Dell Inspiron 15, 5570, LCD issue

Thanks mcplslg123 for your reply... what other voltages should I check at that eDP connector ? The +LCDVCC (at U1, pin1) is 3.1V ... beside backlight missing, also I don't notice any video signal on the panel ...the replacement is LM156LF5_Panda screen vs original AOU B156HAN01.2

[mcplslg123]

Re: Laptop Dell Inspiron 15, 5570, LCD issue

+LCDVDD, LCD_BRIGHTNESS, BLON_OUT_C,DCBAT_LCD-These are responsible for backlit issues. Since the error message is lcd panel not connected , i doubt you have missing EDP_TX0/TX1 lines.U1,Pin4-LCDVDD_EN missing?? First confirm these measurements and be careful while measuring.

[SMDFlea]

Re: Laptop Dell Inspiron 15, 5570, LCD issue

Those panda panels are used in gaming laptops,and they are poor quality.Can`t find a datasheet for the exact model so don`t know what the refresh rate is or how many eDP lanes it needs. The AU original panel runs at 60Hz and 2 lanes .

[suiramix]

Re: Laptop Dell Inspiron 15, 5570, LCD issue

Thanks again guys,...agree with you,... the new panel looks cheap but was purchased from laptopscreen.com (matte version)...I will measure those voltages with the LCD panel connected and get back to you!

[suiramix]

Re: Laptop Dell Inspiron 15, 5570, LCD issue

So, the voltages at eDP connector are:
pin7,8, +LCDVDD = 2.95V
pin27, LCD_BRIGHTNESS =3.20V
pin28, BLON_OUT_C =3.10V
pin1,4 DCBAT_LCD=13.11V
and pin4 U1=3.39V
My guess is the recommend (Panda) screen is not compatible with original AOU !
However I did boot up from USB Ubuntu with this new screen connected and "build in display" was listed on control panel with 1920x1080 resolution, but again no video and no backlight!

[mcplslg123]

Re: Laptop Dell Inspiron 15, 5570, LCD issue

With the measurements above,you should have got backlit on even if no data on screen. You are not even having backlit-correct?? If so, doubt goes towards the panel itself being either bad or incompatible.