820-3437 power rails cycling

[tlough75]

So this is probably one of the strangest repairs...I get a green/orange light on the charger and when I measure PP3V42 on pin 2 of L7095 and I get a steady 3.43v. But when I measure PPBUS_G3H I get 8.56v but then it dips every second down to 7.95, then back up to 8.56, then back down. It draws about 30mA then goes up to 100 mA, then back down. Anyone have experience with this type of issue? Thanks in advance!!!

 

[2informaticos]

PPDCIN_G3H fluctuates too?
Post exact resistance between pins 17/18 and 27/28 of U7100.
3V3_S5/SUS, or other voltages pulsing?

 

[tlough75]

PPDCIN is a steady 18.5V
U7100:
17/18 3.1 Ohms
27/28 20.3 Ohms
3v3 is pulsing too.
there is an audible "tick" coming from the board.
I am reading a 0v drop to ground on L7430 if that helps.

 

[2informaticos]

"I am reading a 0v drop to ground on L7430 if that helps."
I don't really understand you.
Post diode mode to ground there; red probe on ground.

Please post accurate info.
I asked you about TWO 3.3V rails.
Also check voltage for other power rails.

PM_PWRBTN_L reacts (drop pulse) when trigger SMC_ONOFF_L signal?
Use R5115/16 pads, instead of power button.
If yes, check if ALL PM_SLP_Sx_L signals react to.

 

[tlough75]

Ok, I decided to UC the board and now it appears to be running... I'm thinking there was crap under the SMC.

 

[tlough75]

going to put it back into the case and run it for a bit. Thanks for the help.