MBP 820-3113. Liquid damage.

[gcain]

[FONT=&quot]Significant liquid damage with pins 4 & 5, as well as the traces totally dissolved (Red wine, Arg!).

[FONT=&quot]Replaced U5410: Pins 4 & 5 completely burnt out.[/FONT]
I ran a wire from U5410 pin 4 to R5410 Pin 2 and from U5410 Pin 5 to R5410 Pin 3 to try and get around the traces being burnt out. (Can someone confirm this is right please?!)

Replaced R7403 which was dead.


Board now powers up but fan runs high & R7403 is reading erratic voltages.

Can someone suggest some measurements I should be taking?


I'm new to the board repair business and know enough to be dangerous.
With a little direction though I should find my feet really quickly. All suggestions and input appreciated.[/FONT]

 

[dukefawks]

U5410 is not important right now, the board will work without for now.
Measure both R7402 and 3 from F7040 to the actual pin on U7400 to see if the traces are ok.
ALL_SYS_PWRGD present?

 

[gcain]

Any suggestions on what to check next?

 

[gcain]

Thanks for the instructions!

U7400 doesn't have a pin 48, it stops at 40 (or 41 really) right?

 

[gcain]

[SUB]Reading from the wrong board...[/SUB]

 

[gcain]

Ahhh No!
I got two boards mixed up!!

I'll get the proper readings in a moment.

 

[dukefawks]

F7040 to pin 1 should be 182K and pin 48 should be 150K, check again.

 

[gcain]

I cleaned the points and checked again.

I'm getting 30 to 40 Mohms (it's not a stable reading) on both pins.


(Going to start checking every component btween U7400:in1 and F7040)

Happened to get another 3115 in today and checked U7400 to F7040; Yep, 182 & 150k Ohms exactly. :/
This is good though, I have something to look for now.

 

[dukefawks]

Corroded pins 2 on each resistor or completely dead resistor.

 

[gcain]

Can I just run a jumper wire across?

 

[dukefawks]

Not to F7040, but you can take it from C7513 if continuity to F7040 is good on that one.

 

[gcain]

F7040 to C7513:in1 is 0Ohms.
C7513:in1 to R7402 & R7403 is 6MOhms.

So I'm guessing if we jumper-wire from C7513:in1 to R7402 & R7403 I should have power back there.

Yeeew, going to give it a try and report back.


Edit:
Could one of the capacitors on that line be faulty and causing this issue?
Maybe the issue is a component and not the trace.

 

[gcain]

Still no chime or picture or ram-beeps.

I'm getting the 12.6v at R7402 & R7403 now, but the behaviour is exactly the same.

 

[aprendiz]

Do you have VCORE on L7510-7520??

 

[gcain]

Negative.

I get 1.3mV on each side of L7510 & L7520.

 

[aprendiz]

CPUIMVP_VR_ON present on pin 47 ???