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Video out to screen, no backlight, fuse was blown I have traced it back to Q7707 and all the pins look correct other then pin 5 EDP_BKLT_EN which is zero, The schematic says this goes to a pin on the CPU, Could just that pin on the cpu be damaged as it appears to work fine other then backlight...

I have an 820-3437 that had liquid damage. It was pulling no current and no led on charger, I cleaned up corrosion U1900, removed and cleaned it and replaced. I now have PP3V3_SO and PP5V5_S0 and am pulling 136ma on the power supply. My vcore is only .085v, I can't seem to find anything pulling...

These are 'good tested board' from different sellers, Just wanted to make sure it couldn't be something else other then the logic board. I guess need to just part out all the good parts and not try to find working logic board.

Anyone think of a way the dc in board can be bad and cause the cpu to overheat?, usually boot up one time then freeze up and not work again till it sits and cools. Either that or I am very unlucky with boards as I have had 3 do the exact same thing... This one is pulling 1 amp through the power...

Found bad pad and trace, ran jumper wire . The connection between R7425 and pin 15 of U7400 was gone. Not really corrosion but pad looked a little tarnished, scrape the black coating off trace and copper looks like melted away. I now have continuous fan spin, pulling about .6 amps but no chime...

Checked all 22 of the resistors, they look good, checked all the pins on 6100/01 only the ones that should be ground were to ground. No visible corrosion. Just have the traces to check left to do. I take it this is failing when trying to load the bios?

U1950 When first plug in charger (These are just watching display for highest value, before went to second values) (Did not use max/min function) 1 3.4v 2 3.4v 3 3.4v 4 0.040v 5 3.4v 6 3.4v 7 3.4v 8 3.4v After charger plugged in 5 sec and...

No history, I wish I had stuff brought in for repair, but I am learning on boards listed as for parts or repair on ebay so I am probably buying donor boards :). I could find no liquids or corrosion on the board and no sign anyone had tried repairing it.

Both 7 and 3 act just like 1, voltage when charger connected for brief second, then nothing.

ALL_SYS_PWRGD goes to 3.3v then zero on pin 1 of U1950 PPVCC_S0_CPU on R7320 pin 2 peaks at 1.8v then zero Both come up with fan spin, then go to zero when fan shuts off. Just to make sure I am saying this correct, the fan spin and the voltages come up when I connect charger, then about 1...

After fan stops pulling about 24ma from the charger. Going down the power rails I have everything till PP5V_S4RS3, on U7501 it is 5V while fan spins, then down to zero when fan stops on pin 2. It looks like something stops telling it to turn on. Any suggestions?

With the one heat sink bar hard to tell and already had it off once, Guess I should of checked it then. I guess it goes to the parts bin now. Thanks.

Well it gets really hot and resets, didn't think the air had a gpu but I guess the 2010 did. Does this have a bad gpu or what else causes it to get very hot and then not finishing booting. I was fooled with filevault and got the logon screen but that is only efi, it never seems to complete...

That was it, played around with the ribbon cable on the track pad side and power button started working. I think just going to see if can find a top case, screen looks great.

Duh, even in red... I missed the _L I was thinking it was P3VS3_EN. I knew some required starting, this is first one I have had. That looks like it makes it easy as it started and pulling 1 amp from charger, The keyboard looks nasty I bet the on off button is not working... Thanks!

On Q7910 I have 3.3v on pins 3 and 4, but pins 1,2,5,6 are all zero and not shorted to ground. It looks like Q7910 is bad, anything else I need to check? Board is pulling 20mA from charger.

I would look at pins 4 and 5 at the battery connector, it looks like a problem with those data lines and it can't detect the battery, It appears the charger and battery line tie together, so maybe when it can't detect the battery it won't turn on, but once it is on, the battery power is bonded...

Thanks, that is what I suspected but wanted to confirm. No plans to attempt GPU replacement at this point.

First I will preface this with I am new to macbook repairs, I have the above referenced board that was showing fine diagonal lines, get almost to desktop then reboot, hot in center of board. I took this to be the graphics chip problem, since I am new and need practice I took the heat shield off...

Thanks all.