820-4924-A No Backlight....

2click

Member
Sorry Duke,

Just to make sure here, you used a complete different case with trackpad cable and everything?
Completely different case with trackpad and a battery that is dead.

At least the battery in that one has seen better days but that will not cause the fan to run high.

Check diode mode on both I2C_TPAD_SDA and SCL lines on the trackpad connector. There is continuity

The trackpad is working normally in the boot screen menu? Fan still goes on full after 20 seconds? It works fine in the boot screen or in the diagnostics screen... and yes, it goes full speed after 20 sec.
 
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dukefawks

Administrator
I need the diode mode values on those SDA/SCL lines. Better yet, post all the diode mode readings for all pins of the trackpad connector.

You did use another trackpad cable too?
 

2click

Member
Update: I did use a completely different computer case with different keyboard and trackpad including the flex...
PINS
1, 3, 5, 7, 9, 11, 13 = 94.2
2, 4, 6, 8, 10, 12, 14 = .2
19 = 14.53
20 = 9
21 = 9.98
22 = 142
23 = 10
25 = 10.39
26 = 135
27, 29 = 8.46
28 = 123.8
35 = .363 (it says to be M ohms)
36 = 77.3
37 = .360 (same that happened on 35)
38 = 8.90
41 = 11.4
42 = 45
43 = 121
44 = 43
45 = 11.35
46 = 136
47 = 54

thanks for the help!
 
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2informaticos

Administrator
Staff member
Revise your post.
These values have no sense; I don't believe you have short to ground on them all...

For example,
"25 = .8 ohms"
if that is diode mode (as dukefawks asked you), delete "ohms" mention; if you really had 0.800 reading.
Do NOT forget, diode mode to ground must be checked with red probe connected to ground; touch test point with black probe.
 

2click

Member
I'm sorry Duke, should I try diode mode to ground? red probe on ground and black on pin? Is that what you need?
 

2click

Member
I used the diode mode, red probe on ground, black probe on the pins... hope this is the right way to do it...

1, 3, 5, 7, 9, 11, 13 = OL
2, 4, 6, 8, 10, 12, 14 = 0
19 = .674
20 = .618
21 = .535
22 = .655
23 = .542
25 = .497
26 = .449
27, 29 = .339
28 = .408
35 = .355
36 = .374
37 = .353
38 = .613
41 = .537
42 = .411
43 = .510
44 = .388
45 = .516
46 = .667
47 = 0

Thanks for the patience....
 

dukefawks

Administrator
Nothing looks really worrying there.

Also going back to the diagnostic error there I see a NDT001 which would indicatie a Thunderbolt failure. What is the exact history of this board as I suspect this was messed with and not just that backlight problem that was fixed.

Can you do a PRAM reset and run diagnostics again? Do you have another LCD assembly to try with?
 

2click

Member
Hi Duke, the customer said that it just didn't turn on one day... and the motherboard looked completely clean, some dust on it like usual, but no liquid damage. I tool off the TB chip because I saw the solder a little dirty, as the climate here is very humid, that happens a lot. I cleaned it and put it back on.
I have 2 computers on that model now, so that's why I was able to try a different track pad and monitor, I changed the MB to the other computer?s case and had the same problem, I will do the PRAM reset and run the diagnostics again, I?ll send the picture of the results... Thanks

Update: in fact, I remembered just now that I took off the display port chip (U9750) because it was getting hot, but I don't know how to resolder it again because it seems like a IC and I don't have a stencil for it... Can that be a problem?
 
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