820-00165 liquid damage - No green Light

Ryanlen2

Member
Liquid damage near SMC region and Q7010, U7090. C7092 area. No green light on this.

PP3v42 - 2.936V
DCIN - 15.4V
PPBUS - 8.18V

PP3V42 in diode is .303

SMC had some damage by C5010, C5017, C5002, C5007, C5008.

Slight short in PP3V42?

Thanks!
 

JohnB8812

New member
Is PP1v2_S5_SMC_VDDC shorted to ground? Very common for one of those tiny guys to short and cause 2.9 volts on PP3v42.
 

2informaticos

Administrator
Staff member
You don't have direct overcurrent situation on 3V42 power rail.
Should be some component connected to this line; i.e. SMC, or mentioned small caps from PP1V2_S5_SMC_VDDC line.
There are also other chips connected, like U5110, U1900, etc...

First check correct value for R7095/96.
Also check for short, or low value at pin 1/U1900 and pin 8/U5110.
 

Ryanlen2

Member
Took PP1V2_S5_SMC_VDDC diode measurement @ C5010 and C5017 and got around .300 which was a bit lower than .510 that I get on a working board. Replaced those components and diode measurement was still at .300 on PP1V2_S5_SMC_VDDC. So I reflowed the SMC and diode measurement is now @ .475 on PP1V2_S5_SMC_VDDC. Green light is back and board turns on. Only thing is that it turns off while booting to ssd and may or may not turn back on right away. This occurs with AC or Battery power. The last time this occured I hit the board with some hot air and it turned on. This however could just be coincidence. Looks like I will be doing some more measuring in tha AM. Thanks for your help, its greatly appreciated guys.
 

2informaticos

Administrator
Staff member
In this case I recommend you to reball the SMC.
Its reaction after heat denotes accumulated crap underneath.
You can try first to put good flux and heat SMC untill 180-20 degrees.
No need to melt the balls, just to burn the crap.

You may also need to apply the same process for PCH/CPU...
 

Ryanlen2

Member
Hi, SMC has already been changed from donor. Same issue present. I will report that pad "93" of U5000 is in very poor condition. Maybe this isn't making good connection with new SMC?? I do have 1.2 V on pp1v2_S5_SMC from C5011, 13.

Have a good one.
 

2informaticos

Administrator
Staff member
That 1V2 voltage comes from pin 93 of SMC; so yes, there is good contact.

"You may also need to apply the same process for PCH/CPU"
Possibly crap there, if the board reacts to heat.

Which signals did you check when the board doesn't want to turn on?
Try to start in SMC bypass mode.
 

Ryanlen2

Member
Hi!
I went along and did the cleanup under PCH/CPU and that resolved the turning on issue, but it is still shutting down at random times during boot. I have found that this happens when ANYTHING is plugged into the KB/TP connector. I have tried new cables and trackpads and keyboards. The connector looks ok but I am going to change it anyway. If that does not resolve the issue then most likely issue with one of the _s4 lines? Thanks guys, have a good one.
 

2informaticos

Administrator
Staff member
Possibly crap on the power button.
Disconnect keyboard only, from trackpad circuitry.
Start the machine with R5116 pads, or connect only charger (no battery).
If it works good with only trackpad, then power button is the culprit.
You can also monitor SMC_ONOFF_L signal, when keyboard connected.
It should stay (steady) at 3.3V...
 

Ryanlen2

Member
Okay, so replacing KB connector resolved the issue. Thanks!


Quick question if you can. How does PP1V2_S5_SMC_VDDC work and how is it related to pulling PP3V42 down. In other words how did you know to check there?
 
Last edited:

2informaticos

Administrator
Staff member
PP1V2_S5_SMC_VDDC is a voltage generated by SMC for internal use.
Is available outside only to connect few caps for better stability.
An overcurrent there (caused by low resistance to ground) can be reflected on the 3V42 line, as is the main power rail of SMC...
 
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