820-4924 no Keyboard and Mouse in OS after login?

[Fizzl92]

Hello,
this 820-4924 was waterdamaged. The customer claims, that he dryed it and it was working after that except one problem. He can start it and log into his account but as soon as he enters the OS Keyboard and Trackpad aint working anymore.
I cleaned the (minor) corrosion and put it in the ultrasonic after that but no change so far. I know that keyboard and trackpad are connected via USB in BIOS and via SPI in OS (if i dont mixed that up) but would that explain that he can still log in?
I had an Air here with similar problem but on that one i could not enter the password with internal keyboard (while keyboard was working in bios)...
With external keyboard and mouse everything works fine.
Any help appreciated.

 

[2informaticos]

When file vault is enabled, keyboard/trackpad still work on USB mode in password screen!
Check all resistors and traces related with SPI mode activation (page 37).
Check U4910 input/output signals in OSX.

 

[JohnB8812]

Have you tried a new trackpad cable? They fail a lot on this model. If you?ve ruled out parts, then SPI traces and resistors are suspect

 

[Fizzl92]

Thank you for the answer. I dod not know the thing with file vault so i suspected a different problem...
So as this has to be a problem with SPI i checked all resistors and traces but everything is fine. Next i checked every pin of U4910 and Pin 6 was 0V (i suspected 3,3V). I traced this back to R1630 that is measuring fine (89kOhm) but has 0V on both sides. So i followed this to U8010 (as everywhere where PP3V3_S3 should be was 0V - but as the board starts up it has to be there somewhere on the board).
At the end the probepoint between U8010 and R8011 had a tiny crack threw it and fell off the board in 3 parts as i scraped it because i thought that that crack was a hair. So i ran a jumper and now everything works fine. Thank you very much.
Mark as solved please.

 

[Fizzl92]

Unfortunately i need to come back to this one. The device was returned to me and mostly works fine. Just sometimes if the machine wakes from sleep (Not everytime) mouse and keyboard wont work (permanent not working mouse and keyboard in OS after waterdamage caused by a broken trace was the original problem). So i am really confuesd by this one. PP3V3_S3 PP3V3_S4 and PM_SLP_S4_L need to be present as the rest works fine. I can even use it with external mouse and keyboard if internal devices wont work... I have no clue where to start here...

 

[shanenin]

did you ever rule out a bad cable?

 

[Fizzl92]

Thank you for the answer. I actually didn?t rule out a bad cable.
The original problem was "no Trackpad and Keyboard only in OSX" caused by an broken trace for SPI enable. And since i fixed that problem the still present problem with the "no trackpad and keyboard after standby" is there it was only there after the waterdamage. So i assumed that it might be a board issue. But i`ll test a new cable tomorrow and hope for the best.
Maybe its just that - maybe i cause it to die a few month earlier than it would have naturallly anyways by unplugging it a few times during the repair^^

 

[2informaticos]

Are you using original Apple 60/85W Magsafe 2 charger???
Do NOT use 1-->2 adapter...
Re-check all SPI traces and resistors for corrosion.

 

[Fizzl92]

This happens from battery aswell. I dont use a adapter for my magsafe. Last time i checked all resistors and traces and put it also in my ultrasonic after i was done with it. So i cant find anymore corrosion.
I also nitoced that if trackpad and keyboard wont work and i press power for 8 seconds it wont boot after that. It turns on, backlight comes up and it also chimes. But no boot and also nothing if i press "alt key" at start. Customer claims that it works again after a few hours or a day and it also works again after i unplugged the battery.

 

[2informaticos]

Do NOT use ultrasonich bath so much; you can damage boards, if incorrect used (no sweep).
Ultrasonic will not rebuild broken traces, but you can got broken traces after.
Also cannot replace corroded components; maybe kick them off.

Be sure all SPI related resistors have correct value and good solders.
Check solders for U4910 and post its voltages when no trackpad/keyboard available...

 

[Fizzl92]

I put every waterdamaged board and boards with eg. new SMCs (lot of flux) in the ultrasonic just to get rid of possible corrrosion under ICs and flux so it looks nice. You mean its incorrect to use sweep or not to use it? I`ll use sweep all the time...
If not working Pin 38 (i measured the TP next to it with everything connected to the board) of J4802 has 0 V on it. If working 3.3 V. So the enable is missing.
Its kinda hard to measure if not working outside the case (even to check if its working or not is hard...) but ill see what i can measure.

 

[Fizzl92]

Update: I followed the missing enable back to U8010. It took me some time to get everything setup and wait for keyboard and trackpad to fail. U8010s input and enabe were there but output was only 0.02 V. I checked for a short but there was no. So i replaced U8010 and to be sure U8050 as it is also connected to PP3V3_S5 and now it seems to work again. At the first boot i got some green glitching colors at the internal secreen but after a restart everything seems to wirk fine. I`ll test this one for a few days and hopefullly i dont need to ask you again for help with this one.
I`ve one more question: You don?t recommend to clean every board after repair in ultrasonic and if you use the ultrasonic only with sweep on?
Thank you very much for the fast reply(s) and the grerat help!

 

[2informaticos]

Always use sweep function.
And do NOT use UC to remove flux from the areas where you can scrub with toothbrush and alcohol...

 

[Fizzl92]

Thank you. And waterdamaged boards after fixing them to make sure there is no corrosion left somewhere that i missed?

 

[2informaticos]

If you don't see any corroded area, why?
Only if you suppose corrosion underneath BGA chips...