HELP: Dell Latitude D620 Compal LA-2791 Rev 1.0 UMA not powering

[vettouch]

I traced what the fault of the motherboard could be and discovered that PU3 got hot (see attached schematic) when the power button was pressed. Boardview can be of immense help. I appreciate all candid assistance.

[Stevedb]

Re: HELP: Dell Latitude D620 Compal LA-2791 Rev 1.0 UMA not powering

If Pu3 get hot then you must check if it outputs are not shorted ld03 , ld05

[vettouch]

Re: HELP: Dell Latitude D620 Compal LA-2791 Rev 1.0 UMA not powering

@Stevedb; I found 4.8v on presumably LDO5 or LDO3 because I don't know how find the exact pin numbers. Also, somewhere on one of the PU3 pins, I measured 3.2v. What can I suspect?

[SMDFlea]

Re: HELP: Dell Latitude D620 Compal LA-2791 Rev 1.0 UMA not powering

@Stevedb; I found 4.8v on presumably LDO5 or LDO3 because I don't know how find the exact pin numbers. Also, somewhere on one of the PU3 pins, I measured 3.2v. What can I suspect?

The PU3 chip will have a dot in one corner,that means pin 1 starts there. Count the pins counter clockwise

Datasheet https://cdn.badcaps-static.com/pdfs/...f508d059dc.pdf

[harshana]

Re: HELP: Dell Latitude D620 Compal LA-2791 Rev 1.0 UMA not powering

@Stevedb; I found 4.8v on presumably LDO5 or LDO3 because I don't know how find the exact pin numbers. Also, somewhere on one of the PU3 pins, I measured 3.2v. What can I suspect?

You will see a dot on the chip. keep that dot on left bottom corner. then pins starting from that dot. left to right.

Here I attached the order.

[vettouch]

Re: HELP: Dell Latitude D620 Compal LA-2791 Rev 1.0 UMA not powering

@SMDFlea & @harshana: I could not find any dot on the PU3. Instead, I discovered that there was a dot on the board signifying pin 1. In the course of my investigations on PU3, pins 7, 9 and few others before pin 14 shorted to ground. I also discovered that on the pins configuration image sent by SMDFlea, GND is on pin 23. I'm confused, someone please help me!