had a 2018 13″ macbook air a1932 in the shop with some liquid damage – would not turn on and the sound was missing on the right side speakers.

turns out that after opening up the laptop, the power button has a tiny little daughter board separate from the main board and is also directly connected to the right speaker. the part number is 820-01124-a.

this board does not have any schematic or boardview available that i’m aware of. i was not able to find anything – if you happen to find it, let me know. send me an inbox.

but upon close inspection, there was some apparent liquid damage. one very suspect area i’ve circled below (actually an “after” photo as i didn’t take a zoomed out “before” photo).

this chip looked very bad and from my experience with other similar chips, knew this to be a problem when it comes to liquid damage.

documenting other areas.

the connector to the main board also had some corrosion in a couple of places.

this corrosion had not fatally killed the connection after a bit of cleaning, they were just fine.

back to the ugly looking chip. this type of chip is a BGA chip. underneath are tiny points of contact – in this case 30 pins, or balls connected this chip to the board. and they are a “magnet” for liquids. capillary action will pull in and underneath the chip any liquid that gets nearby and that’s where a short can easily kill the chip. after ultrasonically cleaning the chip, which is sometimes successful, i took a closer look and found that the solder joint of a nearby capacitor had really corroded badly and was needing a touch up. it didn’t look so bad beforehand, but the cleaning really revealed how much damage had been done.

got out the iron and gave it a fresh bit of solder – which also removes some corrosion.

after testing in the machine, i still had not solved the problem. the machine would now power on with the power button, but we were still missing sound on the right side. this daughter board actually connects nearby to the right side speakers. i began to look closer at that capacitor with my multimeter and found that it was shorted to ground. it also ties into the capacitor next to it. i removed both capacitors and the short to ground was still there, which means that most likely, there was a grounding issue underneath the BGA chip. time to take off the chip.

this is a very tiny chip. one method of repair, is to remove the chip, remove all the balls underneath which may be corroded together and reball the chip, reinstall and see if it takes care of the problem. that the chip may stil be good, just the corrosion has caused it to misfire. the next photo is a close up of the chip after i reballed it. and the chip next to a ball point pen.

tiny…

i’ve got some properly sized balls, but this method is very very hard to do.

i have found that using solder paste with a mask is much much easier. turns out all that effort did not solve the problem, so i started checking around for a replacement chip. found and order some and after installing the new replacement, the daughterboard was once again fully functional. the device would power on as intended and the right speaker was now working.

the chip needed for this repair is the TASS770LB2 or TASS770L82 – hard to tell if that 2nd to last is a number 8 or letter B – i think it’s a B – other people are aware of the problem, so a search for either will pull up some search results. actually the following will yield the best results.

aka TAS5770LB2YFFR TAS5770LB2 YFFRBGA

if you find you need a device repaired, please contact me with some details and we will talk about a solution. thanks for coming along with me on this repair journey!