(347) 552-2258 [email protected]

[SOLVED]820-2530 no green light or s3/s0 rails

ytesfay80

ytesfay80

Member
This board was liquid damaged on the top side of the board. I have cleaned and replaced all of the damaged components in that area such as u6990, r6905, d6905, u6901 plus other caps&resistors.

The magsafe connector on the logic board had some corrosion on the adapter_sense pin which I assume is the reason why I'm not getting any voltage on adapter sense but even when I inject 3.3v on the ADAPTER_SENSE pin of the magsafe and plug the charger in I still get no green light except for a very dim one. I get 3.4v on pins 1/4&5 of U6900 but still no green light and R6929 measures good.

I have used 2 different known working magsafe boards.

I have 12.6v on PPBUS_G3H and 3.3v on PP3v3_S5 but when I jump the power pads to turn this on nothing turns on.

Resistance to ground on Pins 1/4 of Y2810 is around 11.5Megaohms.
 
Last edited:
ytesfay80

ytesfay80

Member
Update: I ultrasonic'd the board and plugged in the charger afterwards and I got a green light. I jumped the on off pads and the fan spun so I assumed this was working so I put it in the assembly, plugged the cables in then the battery. When I plugged the charger in the light was dim and after a little while I noticed R6905 was sizzling. Under the microscope when I plug the charger in R6905 gets so hot to the point where the solder on the pads melt and if I touch it it will move.

I put another R6905 on the board and again it did the same thing.
In diode mode Pins 6&8 of U6990 are 0.004v to ground. PP3v42_g3h is around 0.30v to ground and R6905 is 0.66v to ground.

The pads on Pins 6/8 of U6990 were gone and I had to run wires under the chip so I'm not sure if that is causing this short and previously Pins 6/8 of U6990 would start smoking a little but for some reason the short went away.
I replaced C6990 before so I don't think that could be causing the short.
 
Last edited:
ytesfay80

ytesfay80

Member
As soon as a I plug the charger in R6905 starts smoking up and I didn't want to let it cause further damage but for that quick second I tried to measure and I didn't get any voltage on C7771.
I think my issue right now is that Pins 6/8 of U6990 are shorted to ground and I'm not sure why. I am no longer getting a green light. Once I get a green light this should start working again.

PP3v42_G3H is 0.32v in diode mode.
 
ytesfay80

ytesfay80

Member
I removed U6990 and C6990 but the short on PPVIN_G3H_P3V42G3H is still there. The only difference is that now in diode mode it went up to 0.014v.
The pads for Pins 6/8 of U6990 were gone so could the short be inside the board and if so is there anything I could do to get around it?
 
ytesfay80

ytesfay80

Member
I attached an image of the area.
dukefawks
When you say "lift all connections" what would be the best way to go about doing that?
I would just give this back to the customer but I know it works because I was able to get it turning on right after ultrasonic cleaning the board. It was once I put it in the housing and plugged everything in that it did this again.
 

Attachments

  • IMG_3782.JPG
    IMG_3782.JPG
    6 MB · Views: 0
Last edited:
ytesfay80

ytesfay80

Member
Okay I ran a bunch of wires to get around the short and now I get a green light and the fan spins when I short the pads.

I get 1.06v on C7771 and L7770 but should I replace C7771 because I believe they cause issues and if so what do I replace it with?
 
You must log in or register to reply here.
Top