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This board sucks. But I want to figure out what is wrong so I can document it.

Replaced those and no change

ok

Confirmed all pins around U6990 are connected to the vias around it and touched up solder joints. What other components around it could influence it not to put out PP3V42_G3H?

yes. I wonder if I need to order some new U6990 ICs vs pulling them from donor.

So weird. I got PP3V42 and PPBUS to show up for a min, then it went away again. Also, the magsafe light fades away until I turn off then turn back on the power supply. Even when they showed up temporarily, no fan spin. I'm wondering if maybe something is pulling it down. Or if the SMC is bad.

Ok, changed C6991/C996 and still same.

changed U6990 twice, same result. will change caps next. tricky area being next to ram slot.

0.341V

U7000: 1: .004V 2: 18.25V 3: 4.38V 4: 4.38V 5: 0V 6: 0V 7: 0V 8: 0V 9: 0V 10: 0V 11: 0V 12: 0V 13: 0V 14: 0V 15: .142V 16: 0V 17: .773V 18: .751V 19: 5.1V 20: 5.1V 21: 0V 22: GND 23: .672V 24: .672V 25: 4.79V 26: 17.83V 27: 18.1V 28: 18.1V

U6990: 1: N/C 2: 3.8V 3: 16.7V 4: 18.3V 5: 0V 6: 0V 7: 18.3V 8: 3.79V 9: 0V 10: 0V

I have 18V on both pins of F6905. Will create another post of voltages for U6990 and U7000.

PP3V42_G3H: 0V PPBUS_G3H: 2V 3V3_S5: 0V 3V3_SUS: 0V Also, The magsafe light fades after about 35 seconds.

So I have on the bench an 820-2936 tonight and It has me stumped. With board only out on the table, when I plug in a MS I get no PP3V42 but has a light, PPBUS_G3H is 2.6V. On U6990 I'm getting 18v on pins 4 & 7, but no PP3V42_G3H. I replaced U6990 and at first it seemed to work, had MS light...

I get USB activity because I am booted from external drive. After the initial crash I have not been able to get it to do crash again, just the backlight issue remains. Going to see if I have a test LCD.

yeah for the most part. It did glitch out once. By that I mean the Apple logo would come up then the screen would blink, then the Apple logo would come back. It did that about 5 times before I tried to shut it down with the power button, which is not working either.

On the bench I have an 820-00138 that has a strange issue. The backlight flickers and turns off, or stays on. BKLT_EN_R is 3.3V and BKLT_EN_L is 11V when computer is turned off but when I turn the machine on BKLT_EN_L goes to 7-8V and stays, even if I close the screen down. Does this mean U7701...

I meant serial numbers not passwords.

Yeah I tried that procedure. Still would not work. I ended up replacing the IC. It now will let me do a PRAM reset. Customer doesn't care if passwords do not match since it is out of any kind of warranty. I'm assuming either a corrupt BIOS or chip.

So I have an 820-2530 That is EFI Locked. I tried to perform a PRAM reset but it will not do it. When I plug in an external KB it will respond to me hold option to see the EFI padlock, but any other key combos I get nothing. I hooked and External drive to it and can see usb activity, I also...