Macbook A1278, no charge, no magsafe light

[inflex]

Client machine, initially no power up. Swapped battery and magsafe charge port, can turn machine on now (probably since PRAM is now powered by battery with 27% charge) but still the magsafe charger light is off (not dim either that I can see).

Tried known working original charger, same issues. Tried reset the system with the configuration reset key combo, no avail.

With charge in the battery the unit will turn on and run normally. *SOMETIMES* it'll say it's running off mains power but not charging the pack (but most times it just says it's running off the battery). At no time does the magsafe plug light ever turn green or orange.

[highpulse]

Re: Macbook A1278, no charge, no magsafe light

seems a bad charger Ic . what is your experience in fixing laptops ? feel allright to remove and replace components ? wich board code it is for we can help you out .
for your symptoms this could be causes by a few things .
charger works as a switch , it will receive info from SMC saying out the board will run , or thru battery or thru DC - once the internal ic switch is dead , computer cannot manage more the switching option . usually U7000 ISL6259 (depending on board code)
alltough another place to make sure all is ok is with 1_wire_overvoltage circuit , if this circuit is not ok , it will not display the adapter sense (light)

so best thing , chek board code for us ,for we can try to help you out , but if you dont feel free to replace components then you should touch :P

[inflex]

Re: Macbook A1278, no charge, no magsafe light

Highpulse,

Which code is the board code? I've got a sticker that's placed on the top side of the DDR sockets?

Pretty much anything except large pin count BGA I'm fine with. I can *remove* BGA but not so great putting them back down.

[highpulse]

Re: Macbook A1278, no charge, no magsafe light

nop , its a code pratically of the same color as the board lol , i know its a pain in the asss , but if you chek carefully all over the board in certain position you will see a code starting by 820-xxxx-x need this code

[alihomee]

Re: Macbook A1278, no charge, no magsafe light

normally that code is near the fan but u need to check hard as inflex said its hard to find because of same colour as mobo.............

[inflex]

Re: Macbook A1278, no charge, no magsafe light

Thanks for telling me it was near the fan, that made it very quick to find.

820-2936-B

( There's also HF/e1 ) close by too.

[inflex]

Re: Macbook A1278, no charge, no magsafe light

Photo of the board - http://ctpc.biz/repairs/mac-001.jpg

[Nasir Raja]

Re: Macbook A1278, no charge, no magsafe light

Hi check 3.42v on U6990 LDPR (power buck) or check 3.42V on L6995 if 3.42v present, Check 12.3V on F7440 (FUSE) i attached board viewer hope this helps.

[inflex]

Re: Macbook A1278, no charge, no magsafe light

Thanks for that Nasir, I'll have to install OpenBoardView to look at that on my only windows machine in the workshop.

[jcorkin]

Re: Macbook A1278, no charge, no magsafe light

This may sound weird inflex but I had a similar issue with my macbook pro. What I found is if i plugged my charger into another mac and let it charge that mac for awhile I could then plug it back into my macbook pro that wasnt charging and it would begin charging. Not sure on what the issue with mine was as it now seems to charge fine but for a month straight it would not charge. My charger would maintain power to my macbook pro but wouldnt actually charge the battery at all. If you have another mac that uses the magsafe give it a try.

[inflex]

Re: Macbook A1278, no charge, no magsafe light

Hi check 3.42v on U6990 LDPR (power buck) or check 3.42V on L6995 if 3.42v present, Check 12.3V on F7440 (FUSE) i attached board viewer hope this helps.

Just letting you know that I managed to build a linux version of the boardviewer (OpenBoardView), so now I can view things, thanks.

[inflex]

Re: Macbook A1278, no charge, no magsafe light

Found the first issue... U6901 has no power likely because the Vcc pin is corroded. While I don't have a spare parts board I can at least get replacements from Element14/Farnell ( NXP XC7SET08GV seems to be a suitable match to the Toshiba unit ).

Having access to the schem + board + the linux edition of OpenBoardViewer, *and* watching a lot of Louis Rosmann's videos, specifically this one https://www.youtube.com/watch?v=sI7r...cUARjhJZ1AV8CZ zoomed me in on the right area.

Soon as the replacement chip arrives I'll let you know how it goes.

[inflex]

Re: Macbook A1278, no charge, no magsafe light

Some more probing today while I was waiting around, one thing I noticed is that unlike the "usual" failure mode, I do seem to be getting power to the U6901 but pins 1&2 (SMC_BC_ACOK) are a little... strange. I'm reading 0.65V on it. I checked R5087 and I have the 3.42V ( PP3V42_G3H ) on one side (good) and the 0.65V on the other, however I'm not overly inclined to believe that the resistor is at fault, since I suspect it's just a pullup for the output of U7000, I'm sooner suspecting rather it might be Q5310 which is the PN MOSFET pair which enables the DC in voltage sensing enable.

Anyhow, for now I've ordered replacement Q5310's, 0402 470K resistors, and the U6901 dual-input NAND. Just more things to add to my sizable, but never sufficient collection of parts :\

[inflex]

Re: Macbook A1278, no charge, no magsafe light

Turns out it was U6901. Replaced it tonight and finally I get a green light and orange charge. Excellent.

Amusingly, the replacement U6901 I ordered was actually about 4x too large as somehow I picked up the SC-74 rather than SC-70 packaging.

Many thanks to everyone who has assisted along the way.

This project turned in to something significantly larger with the last several weeks being spent working on a fork of the boardview software as well.

[Billrj]

Re: Macbook A1278, no charge, no magsafe light

I've got the same problem. I'm the US and was wondering if you could give me pointers since this is my first stab at board repair.

Thanks

Bill

[inflex]

Re: Macbook A1278, no charge, no magsafe light

BIllrj,

Take the time to watch the video I linked to above, definitely check along the edge of the board for corrosion. 9 times out of 10 there's an obvious hint on the board as to where the problem is. Good lighting and at least a 5x magnification helps a lot.

Get OpenBoardView and the schematic, it helps to find where the parts are.

Paul.