820-3330 corrosion around Q5300 and u7400

Chuck60

Member
Hi I received a board with liquid damage in 2 areas

1st Area:
u7400 in area CPUIMVP_TONB (R7403,C7441) AND CPUIMVP_ISNS1_P (R7406,R7466) the resistors #’s are just to pin point area of corrosion

2nd area:
Q5300 and R5314

I get a green light and quickly the light goes out in a split second.

I tested the
PPBUS_G3H 320 Kohms
PP3V42_G3H 1.79 Mohms

Lastly, I have another board here that chimes just has audio port issue. shouldn’t a 2011 A1286 screen fit this model? The lvds connector is silver ipex not gold ? Should I assume it’s 1680 x 1050? Or the standard resolution? It won’t go in so I’m assuming no. but I could’ve sworn I’ve tested another 820-3330 in my test enclosure in the past. Anyway thanks in advance
 
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2informaticos

Administrator
Staff member
Boards should be compatible.

You forgot to mention actual voltages for 3V42_G3H and PPBUS_G3H.
Do you get steady 3V3_S5/SUS?
 

Chuck60

Member
PPBUS_G3H = 1.7v
PPDCIN_G3H= 1.7v
3V42_G3H =0v
3V3_S5/SUS=0v

R6929=0v SMC_BC_ACOK

Also on this board I know that R7403 is reading “OL” R7402 is 180k so I know that R7402 is good. but I haven’t changed it till I resolve the issue that I suspect is on the 3.42V line. The mage safe flashes and instantly goes out.
 
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2informaticos

Administrator
Staff member
You are missing even 18V5_DCIN, what do you expect to get there???
How did you arrived to CPU power supply if no voltage at all on the board???
Did you check F6905 at least?

I can suppose input leakage, but is better to see eaxct ohm resistance for R7080/81 and R7085/86, measured onboard.
 

Chuck60

Member
Yes F6905 is good same 1.7v at fuse
R7080 =99.2k
R7081 = 61.4k
R7085 =468.3k
R7086 =330k

R7051, r7052= 3.2ohm
R7021, r7022=20.5ohm
 
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Chuck60

Member
There was a droplet of corrosion I cleaned up by q7080 when I started also there’s some small corrosion by u7940, u7400 it’s like it hit all the best parts of the board :(

honestly I was gonna change q7080 as soon as I received this board but since its so close to u5701and j5800. I was hesitant. Even though I’ve done it before. it’s almost impossible for me to replace this mosfet without melting anything:(
 

2informaticos

Administrator
Staff member
Resistor values don't point to Q7080; but still possible.
Try first another DCIN board.
Also check voltages using lab power supply and 85W cord.
 

Chuck60

Member
Ok I’ll try another dc in board I’ve tried several. I have 2 original 85w chargers that I swap back and forth as my test chargers.
But I will prepare a 85w cord with lab power supply and tell you how much current it’s drawing later on today
Thank you
 

2informaticos

Administrator
Staff member
I don't want to know the current.
Lab power supply, or fake charger can show if there is a leakage problem on input stage.
 

Chuck60

Member
The weirdest thing just happened I made the cord put it to my power supply and it chimed :/ but all my test chargers won’t boot with it. I put my test MagSafe and it MagSafe green light goes out immediately
It’s at 18.4v and drawing 1.13A
I’m not sure what’s going on here these magesafe work on other boards I just tested 3 yesterday and all booted fine. Could the be a data line issue then ? Maybe the smc tells the charger to cut or adapter sense to cut?
 

Chuck60

Member
Ok so I put it to several test and today the day it started doing weird things. It’s acting up there are weird artifacts on a YouTube web page but not on the desktop I will attach a image. I’m using 10600s as I can’t find 12800s memory could this just be a incompatibility issue?
 

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2informaticos

Administrator
Staff member
Resolder U8900 with leaded solder; use soldering iron.
Same issue on internal LCD and external monitor?
 
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