820-3536-A no power. Green light on charger

[galvestonmac]

I have an 820-3536-A that has no power. Green light on charger. Laptop has had spill damage.

PPBUS_S5_HS_OTHER3V3 measured at pin 23 of U7501 reads as 1v. How is this generated?
No PP5V_S5 or PP3V_S0

No PPBUS_G3H at pin 2 of R5400.

My power supply is showing it's pulling .01amps when adapter is connected. Suggestions on where to start?

 

[dukefawks]

So PPBUS is missing. Short to GND on PPBUS? Checked around the ISL6259?

 

[galvestonmac]

I have PPBUS coming in at the DC in jack and through the F7700 fuse and surrounding capacitors at 18.5v. It seems to be missing when it goes to the other side of the board. What's normal reading in diode mode for GND & PPBUS? Will look around U7100 when I get back to my shop.

 

[dukefawks]

PPBUS measurement varies by board, just check it and it should not be shorted at least. PPBUS is certainly not coming in at the DC jack, please look at the diagram and avoid such misunderstandings. PPBUS is generated by U7100 from DCIN rail.

 

[galvestonmac]

Short on PPBUS to GND. Also short on C7125 pin 2 GND and via broken U7100 and pin 23 to pin 2 C7125. Think this one will go to the donor pile!

 

[dukefawks]

Uhm, could be as simple as U7100 and the FET. Remove F7140 and see if the system side is OK.

 

[galvestonmac]

Will do. Thanks!

 

[galvestonmac]

Removed F7140 and I get .71v on pin 2 & 0v on pin 1
.506 Ohms on pin 2 diode mode
.045 Ohms on pin 1 diode mode

 

[dukefawks]

So the short is on the ISL side which is good! Replace ISL and Q7130 and check all resistors and traces around the ISL.

 

[galvestonmac]

thanks. i have the ISL. Do you know of a source for the Q7130 MOSFET? DigiKey and Mouser don't seem to have it in their inventory. I have a few donor boards but I don't trust them for parts in that area.

 

[dukefawks]

Donor boards are fine for that. Q7130 almost never dies.