820-00165-A with strange SMBUS_SMC_5_G3_SCL

[apfelimperium]

Hello Community!

I have a liquid damaged logicboard which does not see the battery. Corrosion was around the PP3V42_G3H area and the J6950 jack.
Tested with known good battery.

• R5380 and R5380 both have 2k.
• SMBUS_SMC_5_G3_SCL
  • 2,48V - 3,5V (2,48V is the baseline. Pulses are getting up to 3,5V)
  • 0.5440V diode-mode
• SMBUS_SMC_5_G3_SDA
  • 0-3,42V (looks like normal communication)
  • 0.5400V diode-mode

The SMC does not seem to short the SCL line to GND. It increases the voltage. Any ideas before I have to take a deeper look at the SMC?

Thanks for your help. Nice to be here!

 

[JohnB8812]

Possibly corrosion under the SMC. I'd say inspect for signs of liquid near it.

 

[2informaticos]

Is R6950 OK?

 

[apfelimperium]

No Title

JohnB8812
No corrosion at the back of the LB. SMC and surrounding looks fine.

@2informaticos
R6950 is within the specs (9,88k)

 

[2informaticos]

John suggested corrosion under SMC, not on its opposite side.
So put a bit good flux and reflow to 180-200 degrees; this should burn all the crap.

Resistance to ground looks good on SCLD/SDA.
Change ISL6259 first.
If no result, try other SMC.

 

[apfelimperium]

John suggested corrosion under SMC, not on its opposite side.
So put a bit good flux and reflow to 180-200 degrees; this should burn all the crap.

Resistance to ground looks good on SCLD/SDA.
Change ISL6259 first.
If no result, try other SMC.

Reflowing and changing the ISL6259 did not solve the problem. I will look for a donor SMC.

 

[apfelimperium]

Replacing the SMC did the job At a second Board with the same issue a reflow of the SMC was enought.

Thanks for your help!

 

[JohnB8812]

Nicely done!