820-3115 dead, no light

[jamiehorn1]

Hi i have an 820-3115 that was liquid damaged - mainly to backlight, firewire and tbt circuits.

It powered on and PPBUS was at 12.56.

Fixed all areas then after ultrasonic it now won't boot and no green light

PPBUS is 12.2v
PP3v42 is present
SMC BCACOK is present
SMC_Reset_L is 3.4v

ISL looks good and data lines have 3.42v both sides.

Since i have replaced the SMC but no change to symptoms.

Any ideas on this?

 

[jamiehorn1]

okay everyone get this for a laugh - went for the wrong screw hole when taking it out of ultrasonic - completely destroyed L4901 (literally in half) - why the f i replaced the SMC is mystery.

 

[jamiehorn1]

ah okay so new SMC is not working properly i don't think - i only get 12.15v on ppbus but it turns on? no backlight on the screen though and only 4v on backlight output

 

[aprendiz]

Is BIL working properly?? Are you taking the SMC from a identical board?? Resistance between pins 17/18 and 27/28 from ISL6259?? Seems to be a bad SMC..

 

[jamiehorn1]

Hi, thanks for this. I actually put a new BIL connector on but seems okay, issue persists with no BIL connected. SMC was identical board. ISL measures okay on current sensing.

i will try an SMC next week and leave it at that