820-3115 no pp5v_s5/pp3v3_s5

[ytesfay80]

This board had quite a bit of liquid damage. Initially it had no light on the charger and no ppbus_g3h. I have put flux and heated all the areas with liquid damage.
PPBUS_S5_HS_COMPUTING_ISNS was shorted to ground and the caps on that line were burned on the end so I replaced all of them. The short is gone on there and it now shows 12.58v on it.
PPBUS_G3H - 12.58v
PPVRTC_G3H - 3.45v
PP5v_S5 and PP3v3_S5 both show 0v and there is no short to ground on them.

I have replaced many components that looked bad and they were connected to the 3v3 and 5v rails.
Here are a list of some components I replaced:
Q7820 and the caps/resistors next to it
U2660, C2600, C2660
C7943 and R1923
R3380

U7200(TPS51125) looks spotless with no liquid damage.

I haven't UC'd the board yet so I can save a cleaning.

 

[arghhh]

Is the enable present on pin 13 of U7200?

 

[ytesfay80]

There is no voltage on Pins 1,6, and 16 of U7200

 

[arghhh]

That's not an answer. Is the enable present, low, or non-existent?

 

[dukefawks]

Pin 16 goes straight to PPBUS through R5410 so there should be 12.56V there. R5410 got voltage?

 

[larossmann]

So you have PPBUS_G3H at 12.58v

But you have 0v on pin 16 of U7200. Pin 16 of U7200 is ppvin_s5_5vs3. Check R5410, if R5410 is in-tact, check why PPVIN_S5_5VS3 is not showing up at pin 16 - most likely blown trace, and run a wire to fix.

 

[larossmann]

and duke beat me to it

 

[ytesfay80]

Okay so I had removed R5410 before because that area was sparking up and causing a little flame when I plugged the charger in.
I forgot to replace it so I just put another one on there and the same thing is happening. I can see a little spark at the trace that is to the right of R5410. The trace is now exposed a little from being burned.

In diode mode I measured PPBUS_S5_HS_COMPUTING_ISNS with R5410 on the board and it shows 0.10v. I'm not 100% sure but I believe that number was around 0.35v with R5410 not on the board.

 

[dukefawks]

So there is a short in the board. Good luck trying to dig that out.

 

[ytesfay80]

Is it possible for me to get rid of the short? Should I just start scraping that trace?

 

[dukefawks]

Start digging, but this will probably be trash.

 

[ytesfay80]

Okay so I scraped away at that trace and there is no longer a spark when I plug the charger in and the light stays green.

R5410 shows 12.58v on both sides and here are the new measurements from
U7200
Pin 1 - 0v
Pin 6 - 0.73v
Pin 16 - 12.58v

 

[dukefawks]

So 3v3_s5 present now?

 

[ytesfay80]

Weird. Even though pin 1 of U7200 is 0v PP5V_S5 is present at 4.97v
PP3V3_S5 is also present.

PP5V_S3 is not present.
PP3V3_S3 only shows around 1.16v.

 

[dukefawks]

Why is this weird pin 1 enables the 5V_S3 rails. Voltages on R1800/1/2/3?

 

[ytesfay80]

Oh okay.
r1800 - pin 1: 3.31v pin 2: 3.21v
r1801 - pin 1: 3.31v pin 2: 3.02v
r1802 - pin 1: 3.31v pin 2: 3.30v
r1803 - pin 1: 3.31v pin 2: 3.30v

 

[dukefawks]

Check if 5V_S3 is pulsing. Check voltages on Y2605.

 

[ytesfay80]

5V_S3 is not pulsing at all.
Pins 1, 2 and 4 of Y2605 all show 0v
Pin 3 fluctuates from anywhere around 0.38v to 0.60v.
C2605 was showing around 0.11v but now its showing 0v.

 

[dukefawks]

Connect a battery, does the light turn orange?

 

[ytesfay80]

Initially I connected the battery and the battery indicator cable and only a dim green light would show up.
I then plugged in only the battery and the light would just stay bright green.

I ripped the battery indicator cable in the process so I will need to get another one.

Here are some more measurements I took.
0v PM_PCH_SYS_PWROK
0v PM_SLP_SUS_L
3.3v PM_PCH_PWROK
3.44v - PM_PWRBTN_L
1.17v - PM_BATLOW_L and there was liquid damage in that area.
3.41v - SMC_ADAPTER_EN