[SOLVED] 820-2796 - No Backlight

[menatwork]

F8000:
8.38V


J9000:

Pin 01 - 0.16V
Pin 02 - 0
Pin 03 - 0
Pin 04 - 0
Pin 05 - 0
Pin 06 - 0.13V
Pin 07 - 0.11V
Pin 08 - 0.11V
Pin 09 - 0.11V
Pin 10 - 0.12V
Pin 11 - 0.12V
Pin 12 - 0
Pin 13 - 0
Pin 14 - 0
Pin 15 - 0
Pin 16 - 0
Pin 17 - 0
Pin 18 - 0
Pin 19 - 0
Pin 20 - 0
Pin 21 - 0
Pin 22 - 0
Pin 23 - 0
Pin 24 - 0
Pin 25 - 0
Pin 26 - 0
Pin 27 - 0
Pin 28 - 0
Pin 29 - 0
Pin 30 - 0.17V

Q9807

Pin 1 - GND
Pin 2 - BKLT_PLT_RST_L - 0V
Pin 3 - LCDBKLT_EN_L - - 8.03V
Pin 4 - LCDBKLT_DISABLE - 0.20V
Pin 5 - LCDBKLT_EN - 0V
Pin 6 - LCDBKLT_DISABLE - 0.22

Q9806:

Pin 1 - PPBUS_SW_LCDBKLT_PWR - 0V
Pin 2 - PPBUS_SW_LCDBKLT_PWR - 0V
Pin 3 - LCDBKLT_EN_DIV - 8.14V
Pin 4 - PPBUS_S0_LCDBKLT_FUSED - 8.38V
Pin 5 - PPBUS_SW_LCDBKLT_PWR - 0V
Pin 6 - PPBUS_SW_LCDBKLT_PWR - 0V

R9808:
300K

R9809
147K

 

[dukefawks]

There is no image either!? Does it even chime?

 

[menatwork]

No, i don't have nothing in the screen.

 

[dukefawks]

Check SMC_LID and if that is ok then you first have to try a known good working LCD assembly.

 

[menatwork]

Duke, SMC_LID (3.41V) is ok and i try two different LCD assembly.
Another advice?

 

[dukefawks]

You need 5V coming through U9000, check if enable signal is there.

 

[menatwork]

U9000

Pin 1 - LCD_IG_PWR_EN - 0v
Pin 2 - PP3V3_S5 - 3.30V
Pin 3 - PP3V3_S5 - 3.30v
Pin 4 - PP3V3_SW_LCD_UF - 0V
Pin 5 - PP3V3_SW_LCD_UF - 0V
Pin 6 - GND

 

[larossmann]

if this is not chiming you have a much bigger problem. Are CPU & GPU vcore present? If the internal LCD is unplugged, can you get an image on external monitor?

 

[menatwork]

Louis,
I tested it with external monitor and it worked perfectly.

 

[dukefawks]

Are you testing this with an A1370 assembly? What is resistance to GND on pin 1 of U9000?

 

[menatwork]

Resistance to GND on pin 1 of U9000: 1.003

 

[menatwork]

Yes, and my resistance to GND on pin 1 of U9000 is 1.003

 

[dukefawks]

What is 1.003? ohm, Kohm, Mohm, diode?

 

[menatwork]

Mohm in diode mode

 

[dukefawks]

I have no idea what that means

 

[JorgePayar]

Im not an engineer and I undestand 1.003 MΩ ( 1MΩ)

 

[menatwork]

Sorry, Duke.
Resistance to GND on pin 1 of U9000: 1.005 Ohm (Ω)

 

[dukefawks]

That seems fine. What is the history on this board? Liquid?

 

[menatwork]

no, it's not liquid damage. I just replaced the screen only. screen is good. but does not have video/back light. just sound and external video.

 

[dukefawks]

Was the screen replaced because it was cracked? How did this problem start?