DELL LATITUDE E5450 - +RTC_CELL Leakage

[titomno2]

Hello,

Motherboard (ZAM70 LA-A901P Dell Latitude E5450) not starting (no short on the main line).
When insert ac plug I have noticed the PU100 is hot, 3.3V is only 1.05V (may vary a bit) and also PD3 is hot.
I firstly removed PC1 (after wrongly mesured a short to ground) => Still PD3 ot.
I replace PC1 (when my mistake discovered) => Still PD3 hot.
I removed PD3 and PR1 (PU100 is fine and I can mesure the 5V and 3.3V correctly), I presume there is a leakage on +RTC_CELL.
So I use BoardViewer 2.0.1.9 (Beta) which is a great tool and cad of ZAM70 LA-A901P Dell Latitude E5450 and check every link with +RTC_CELL (FLIR, Measurement but a lot is relatted to CPU so not easy to see short).
I decided to see more clearly to inject 1.8V and low current in order to avoid any destruction and putt the +1.8V on RPE5 pin5 + pin6.
No more heat point on PU100 and PD3, but I see a tiny hot spot on the cpu package AG10 pin heating up and I did not see other hot point.

So I need your help because I know for sure that sometimes the hot point is not necessarely the real defect.

I must alos add I have visually inspected the whole component without seeing any corrosion or overheating trace (discoloration or burn spot).

(Sorry for my poor english, hope everything is clear don't hesitate to ask for clarification).

Link to schematic https://www.badcaps.net/forum/troubl...5450-schematic

Many Thanks

[hwyt0530]

Re: DELL LATITUDE E5450 - +RTC_CELL Leakage

I have two LA-A901P motherboard with the same issue that you descripted. The southern bridge on the CPU chip is gone with short circuit after I tested them.

[titomno2]

Agree, pch is direclty in processor package, I see a hot point when applying voltage, it is clearly dead.