820-3115 not recognizing screen

[Chuck60]

Hi I was working on a water damaged board and I relplaced a few items on 5v/3v rail. It chimes now and I have CPU activity mouse flashing. but no display I’m missing J9000 ( pin 3 0v, pin 4 3.3v) LCD_PWR_EN 0v at U9000 and SMC_LID is 3.4v L9080, r9008, r9009, L9004 all measure good so I’m guessing the lcd isn’t being “seen” I’m using a b133ew07 test screen and a “new” screen cable. if I remember the screen is from a 2010 MacBook Pro so I’m guessing this set up should work if I’m wrong let me know.

 

[2informaticos]

Test voltage at LVDS_DDC_CLK/DATA lines.
Check if both R9008/9 are good.
Be sure to test with compatible screen.

 

[Chuck60]

I’m sorry it was incompatible screen thank you for your time

 

[Chuck60]

J9000 pins
1- gnd
2-.582
3-.582
4-.339
5-OL
6-.610
7-.560
8-.600
9-.627
10-gnd
11-gnd
12-.628
13-.gnd
14-gnd
15-.605
16-.gnd
17-gnd
18-.606
19-.gnd
20-gnd
21-.577
22-.577
23-.577
24-.615
25-.615
26-.585
27-.585
28-.585
29-.585
30-OL

LCD unplugged voltages

Pins 2& 3 0v
Pins 6&7 0v
Pins 17&18 0v
Pins 20&21 3.5v

Lcd plugged in :

Pins 2& 3 3.3v
Pins 6&7 3.3v
Pins 17&18 0v
Pins 20&21 27.99v

 

[2informaticos]

"I have backlight now but no image LVDS_DDC_CLK/DATA= 0v all"
And what this mean???
Looks like you have backlight.

 

[Chuck60]

I’m not sure of what you’re saying.
I have backlight the screen is dim.
Apple logo on back of screen is glowing but no image or Apple/ flashing folder.
You asked me to check LVDS_DDC_CLK/DATA I checked and it had 0v. I thought I was having no image

J9000 pins 24-29

LED_RETURN_1 =.681v
LED_RETURN_2 =.682v
LED_RETURN_3 =.681v
LED_RETURN_4 .=681v
LED_RETURN_5 =.683v
LED_RETURN_6 =.824v

 

[Chuck60]

Ok I replaced it L9080 will try another lcd assembly could it also be the lvds?

 

[Chuck60]

Ok I’ll first try with just the Lvds cable with no screen connected. I will try the screen on another dead board for measurement sake if I get 95ohms then I know for sure it’s the assembly. I’m thinking more like it’s the lvds connector :/

 

[Chuck60]

ok I fixed the dead board and this screen does indeed work. So what can it be ? Bad PCH ? LVDS connector?
Maybe I should Have startEd with what I worked on. Maybe I messed something up I repaired u6100, u7760, u7780, Q3380, f9700. I got these for $5 each so they where missing parts and or badly damaged If you would like pictures of these areas I can send some
Thank you for your help you have taught me a lot and I appreciate your help. I understand how frustrating it must be talking with a novice

 

[2informaticos]

Post voltage and diode mode on pins 2/3, 4, 6, 7, 17, 18, 21/22, with LCD connected.
Do you still get 95 ohms there?

 

[Chuck60]

——--Diode. Voltage
Pin 2 .462. 3.3v
Pin 3 .462. 3.3v
Pin 4 .333. 3.28v
Pin 6 .525. 3.28v
Pin 7 .561. 3.28v
Pin 17 .363. 0v
Pin 18 .351 0v
Pin 21 .570. 26.98v
Pin 22 .570. 26.98v
Pin 22 .570. 26.98v
still 95ohms

 

[Chuck60]

Ok I’ll checked it again. but my working board also had 95ohms. When I connect the screen :/ I powered it up the screen works and powered it down removed from power and test 17/18 it’s still 95ohms.
I understand 2/3, 21/21 pins are connected but I just check it and post The values separately. Redundancy is my life’s work

 

[2informaticos]

Allow 10-15s (at least) after power is removed, before measuring diode, or ohm mode.

 

[Chuck60]

Ok thanks will do