Dell Motherboard LA-K491P no power

[mferna14]

Dear Friends, I am working on Dell Latitude 5420 Motherboard LA-K491P Rev: 2.0(A01) ., Absolutely no power at all. I tried to find the schematics but I think it's not available. Upon observation I saw one chip ISL95860 burnt near the CPU, replaced it but still nothing. The Amp meter is totally blacked out, no display at all. When I connect the battery, at least on one of the battery terminal data lines pins there is 3.3v present. This board is using JHL8040R for each USB-C ports. Can anyone help where to start & if anyome can share the schematics, I would appreciate. Thanks in advance

[SMDFlea]

Read the posts in the LA-K491P schematic request thread https://www.badcaps.net/forum/troubl...ed#post3507736 , the LA-K371P is similar

[mferna14]

@SMDFlea, thanks, I have it with me, the layout & component are mostly different, I have no idea why they say that it's similar. Totally 2 different motherboards & this MB has only 1 USB-C port

[SMDFlea]

Sorry i didn`t check the boards, i just took the comment at face value

[pc_okay]

Hello,

You Connect a usb-c amp metter and you have no display at all?
Did the usb-c charger LED stop Lightning too when you plug charger in?

[mon2]

My schematic for the LA--k491P has the TPS65994 onboard.

[mferna14]

Hello,

You Connect a usb-c amp metter and you have no display at all?
Did the usb-c charger LED stop Lightning too when you plug charger in?

You Connect a usb-c amp metter and you have no display at all? Like I said before... No Display on the amp meter, TOTALLY Blacked OUT.....
Did the usb-c charger LED stop Lightning too when you plug charger in? No power at all, this is why no LED activity at all. DEAD

If any repair tips given to me, I would appreciate.

[mferna14]

My schematic for the LA--k491P has the TPS65994 onboard.

Yes mon2 you are right, TPS65994 is the PD controller on this motherboard. I got the boardview for this model but stil no Schematic, do you have the schematics to share with us.,trouble shooting will be easier. I have already shared the boardview in the schematics for LA-K491P thread.

[mon2]

Yes I do but in a locked PDF. Let me PM you.

[pc_okay]

You have boardview here, you don't need shematic for now:
https://www.badcaps.net/forum/troubl...-0-3-boardview

If amp metter stop working and your charger LED light off, you may have a big short somewhere, that's why I ask you these questions...
Don't forget to check if your USB-C connector are good too.

Then with the boardview you can check resistance to ground (without power) on your USB-C lines: CC1, CC2, VBUS .... then post values jere or make some conclusion.

[mferna14]

@pc_okay., I checked all the USB-C ports & they look like new, no pins damage. I checked all the caps around TPS65994 & they are good. No Short. There is voltage of 3.3 to power on this chip. I am assuming that this chip is defective. I will replace & then inform you'll, thanks dear.